By Mira Grant

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From New York Times bestselling author Mira Grant comes the second book in the terrifying Parasitology series.
The SymboGen-designed tapeworms were created to relieve humanity of disease and sickness. But the implants in the majority of the world's population began attacking their hosts, turning them into a ravenous horde.

Now those who do not appear to be afflicted are being gathered for quarantine as panic spreads, but Sal and her companions must discover how the tapeworms are taking over their hosts, what their eventual goal is, and how they can be stopped.
"A riveting near-future medical thriller that reads like the genetically-engineered love child of Robin Cook and Michael Crichton." —John Joseph Adams on Parasite
More from Mira Grant:


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Table of Contents

A Preview of Chimera

Orbit Newsletter

Copyright Page

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Knowing the direction doesn't mean you have to go.


Boom boom pow, bitches.


November 3, 2027: Time stamp 17:27.

[The recording is substandard, clearly done on a cellular telephone or cheap tablet, rather than any form of professional camera. The lab on the screen looks like it was assembled in a junkyard: mismatched equipment, sputtering lightbulbs, and personnel in stained scrubs that have clearly been worn for several weeks without being washed. All of them have their faces turned away, save for the central figure in the shot, a woman in a wheelchair. Her wavy blonde hair hangs limp around her face but her lab coat is surprisingly clean, given the chaos surrounding her. A palpable air of exhaustion hangs around her. She has clearly made an effort to tidy herself up, to adhere to modern standards of attractiveness, but nothing will disguise the bags beneath her eyes, or the faint pallor of her skin.]

DR. CALE: My name is Doctor Shanti Cale. I am one of the original creators of the Diphyllobothrium symbogenesis organism, more commonly known as "the SymboGen implant," although I suppose that if anyone's talking about it today, you're calling it the cause of the sleepwalking sickness. My co-creators were Doctor Richard Jablonsky, deceased, and Doctor Steven Banks, whose whereabouts are currently unknown to me. I suppose he's still safely tucked away inside his corporate fortress. I know I would be, in his position.

[She pauses, takes a breath, and visibly steadies herself as she returns to her original tone of calm professionalism.]

DR. CALE: I am not trying to shift or dodge any of the blame that is due to me. This confession—the confession of my involvement—appears at the front of every recording we have made since the war began. You will not find information to exonerate me. You may find more proof that I should be reviled by history. It's all right. The broken doors are open now, and I was the one who opened them.

[She grips the wheels of her chair, rolling herself to the side of the shot. The camera does not follow her movement; the recording device is apparently propped on a table or counter. There is a brief blur off to one side as one of the technicians passes through the frame; her face has been pixelated to obscure her identity.]

DR. CALE: At the end of this introduction, the video feed will switch to a compressed data format. Using the following data decryption code will allow you to extract and analyze this week's findings.

[She holds up a small whiteboard. On it is written a string of apparently meaningless letters and numbers. She is careful to hold the whiteboard so that all figures are clearly visible in the shot.]

DR. CALE: I'm afraid this week's results have been less than encouraging. We have retrieved and analyzed four of the so-called "sleepwalkers" affected by the active stage of the D. symbogenesis parasite. All of them demonstrated physiological difficulties, as well as unpredictable and irrational behavior. Analysis of the subjects showed that there had been extensive damage to the soft tissues of the brain and spine during the takeover process, resulting in a host that was unable to reach an accord with the invasive parasite. Unless D. symbogenesis finds a way to begin infiltration earlier in its life cycle, we will continue to see individuals who have been damaged in this manner. At this point, neither the original human host nor the invasive parasite will be able to utilize these subjects as fully functional beings. They are failures of evolution. They are dead ends.

[Dr. Cale pauses and puts the whiteboard down, rubbing her face with the heel of her hand. In that moment, she looks more tired, and more human, than she has since the video began.]

DR. CALE: There are those who will interpret my decision to open these videos with a confession as an admission of guilt. It's not. I just need you to know that my data is as good as it's possible for anyone's data to be, and if there's blame to be given, I need it to fall on me. But I'm not guilty. Guilt involves feeling like you did something wrong, and while I am most definitely to blame, I'm not guilty.

[She smiles, a little sadly.]

DR. CALE: I don't know who's watching these videos, if anyone is. Maybe it's someone from the human side, and maybe it's someone from the D. symbogenesis side, and I'm not going to say which side it is that I'm rooting for, because honestly, even I don't know anymore. I know that I did good work. I know that I made a lot of lives better with what I did. I know that I love my children—all of them, no matter what species they are. I know that I am sorry for what's happening right now, but nothing that happens is ever going to make me regret that I created them.

[Her attention switches briefly to something outside the shot. She makes a gesture with her right hand, which appears to be American Sign Language for "okay." Then she nods, turning back to the camera.]

DR. CALE: Whoever you are, we're ready for you. May you put this information to good use. May you find a way to thrive. And may you, and everything you love, make it through the days ahead alive.

[She grips her wheels and rolls toward the camera, swerving just before she would have run into whatever is holding it. There is a brief stutter in the picture, as if the image were compressing, and the lab is gone, replaced by a several-megabyte flood of data. This onslaught of encoded information continues for ninety seconds before the visual feed abruptly terminates. The audio continues for a few seconds more, then ends.]

[End report.]

September 13, 2027: Time stamp 18:21.

This is not the beginning of the end.

This is the beginning of the recognition of the end; this is the point at which the world could no longer afford to pretend that nothing was wrong. The end began in a thousand places at the same time, sending little cracks through the foundation of mankind's casual dominion over the earth. It was born of hubris, and it started slowly, only to gather in both speed and strength as the days went by. No one who noticed had the power to stop things, and by the time more eyes were on the problem, it was too late.

This is not the beginning of the end. But it is the end of the beginning.

Paul Moffat was dying.

Externally, he seemed to be the very picture of health, the sort of man who could still run marathons and climb mountains, despite being well into his fifties. He had been cited repeatedly as one of the Bay Area's most attractive movers and shakers—an honor that was only partially paid for by his press secretary. As mayor of San Francisco, he had to keep himself looking his best. As someone who was starting to look thoughtfully at the Governor's Mansion, he couldn't afford to slip up even a little. Thank God for SymboGen. Not only were they generous contributors to his war chest—and let's face it, there was always room for another million dollars tucked into the rumble money—but they took care of their friends. His implant was top of the line, genetically engineered for maximum compatibility with his biological profile. His health wasn't something he was willing to gamble with.

"Every man in my family has had allergies, even unto the seventh generation," he said, winning himself a laugh from the largely conservative crowd. They appreciated a good Bible reference every now and then, as long as he didn't go too far and start to slip into proselytizing. The heady days of the twenty-teens were behind them, and while God still had a place in the American heart, He was increasingly less welcome in the political arena. No one wanted to be perceived as trying to drum up another Tea Party. But a few little reminders that Paul Moffat was a man of faith always went over well. "Me, I have two dogs. Big shaggy things. My kids love them, my wife—or at least my wife's vacuum cleaner—hates them, and you know what? I've never had so much as a sniffle. You could say 'there's a man who's had good luck,' but I know better."

Paul paused, smiling genially at the crowd, giving them time to snap the pictures he knew they were aching to take of him. Man of the people, politician you can talk to—he was happy to take whatever title they wanted to apply to him, as long as it was a positive one—and he worked hard to make sure that they were always positive.

Later, the few people who were able to review their shots would notice the odd lack of focus in his eyes, or the way the corner of his mouth was twitching—just a little, not enough to see with the naked eye, but more than enough for the camera to catch. The camera was always looking, and unlike Paul himself, it was never going to lie. Not for the sake of expediency. Not for the sake of anything.

In Paul Moffat's descending aorta, something moved.

Progress through the body was slow, especially for something the size of a mature D. symbogenesis tapeworm. Paul's implant was more than three feet in length, slightly thicker than a ribbon—a ribbon that moved in small, fluid undulations. It pulled itself along more through instinct than anything else, heading inexorably toward the only destination that could fulfill its instinct to protect its newly forming sense of self. The blood flowing around it pushed it backward, but it persevered. Although this implant did not know it, it was the third to have attempted the long, slow transit through the body of Paul Moffat. The first two had chosen the vena cava as a safer means of transport, mistakenly risking their lives on what seemed, in their mindless questing, to be a kinder current. The deoxygenated blood had killed them as surely as they had intended to kill their host. They had decayed and been flushed from the body with no one the wiser.

But this worm, the third worm, burrowed from Paul Moffat's digestive tract up into the largest vein in the body, the vein responsible for carrying life-giving oxygen to the rest of the organism. Passage was slow. That didn't matter. It was, by that stage in the process, also inevitable.

"You see, when I was a boy, I was so allergic to anything with fur that we couldn't even take me to the state fair. Can you imagine that? An all-American boy unable to attend his own state fair because just getting within two hundred yards of the 4-H exhibits would see him sneezing his face off." Paul paused for effect. The audience laughed uproariously.

The pause stretched longer. Paul opened his mouth to continue with his anecdote, and froze. The world seemed to have gone out of focus while he was catching his breath, and now he couldn't get it to come back.

Inside Paul's body, the implant had reached the end of its long and arduous journey. Bit by bit, it forced itself through the small opening at the base of his skull, shoving and chewing its way into the space that would be its new home. With every bite it took, a little more of Paul Moffat—who he had been, who he had dreamt of becoming—was devoured, gone to feed the worm that he had willingly nurtured in his own flesh.

His mouth closed, only to open again. No sound emerged. His aides, who had been relaxed and enjoying the familiar sight of the mayor in his element, began to tense and watch him carefully for some sign of what was going on.

They couldn't see the true problem. The body of the implant blocked vital blood flow to the brain, causing minor lesions and cell death, even as the worm itself chewed larger holes into the surrounding tissue.

By the time Paul Moffat moaned and shambled down from the platform, arms outstretched and grasping for the people in the front row, the man he had been was quite mercifully dead. He would not see his body biting into the throat of a local businesswoman; he would not be aware of the pheromone signals his skin was now emitting as they began to awaken the sleeping parasites in the people around him. He was, in his own strange way, spared.

The rest of the world was not so lucky.


When looking for someone to trust with your health, choose SymboGen. Because if you can't trust Nature, who can you trust?


Here I am.


—I repeat, the city of San Francisco has been compromised. Reports of infected individuals are coming in from all parts of the county, and attacks have been witnessed on buses, trains, and ferries heading into other parts of the Bay Area. At the current rate of exposure, all infection-prepped individuals will be compromised within the next twenty-four hours. USAMRIID's evacuation efforts are ongoing, and are centered around the organization's Treasure Island base. Other rescue and evacuation efforts have been put in place by state and local authorities, but all have thus far failed to gain traction. In several cases, members of the rescue teams have joined the sleepwalkers in their attacks.

The CDC has a team incoming, and all staff currently on the grounds are being scanned for signs of tapeworm infection. Antiparasitics are being handed out by the doctors, along with any prescription medicines which will become necessary once the worms have been purged. It's unclear how much good this is going to do. No one knows how far the infection has already gone.

God, my head hurts.


The structure of the evolving D. symbogenesis parasite is as fascinating as it is horrifying. It seems to change from generation to generation, belying the asexual nature of classic tapeworm reproduction. I'm not sure where the tendency toward mutation was introduced—it doesn't match with any of the admitted genetic sources, and Mom has no reason to lie to me at this point. She got what she wanted, after all. We're here, with her, and the tapeworms are taking over the world.

That's not fair. I'm sure this isn't what she wanted. I'm sure she had more sense than this. At least, I want to be sure


Chapter 1


Dr. Cale's lab might have been concealed in an abandoned bowling alley, but she'd clearly never seen that as a reason for her equipment to be anything less than state-of-the-art. The MRI scanner was kept in a private room, and was as elaborate and complex as anything they had at SymboGen. I tried to focus on how surprising it was to see a piece of machinery that complicated in a place like this as I shed my clothing on the floor and allowed Nathan to help me into the scanning bed. I'd been through this process before. It made it easy for me to lie still and close my eyes, pretending that none of the last few weeks had happened; that everything was still normal, that I was still me, and not the thing that I was desperately afraid I was becoming. Or worse, the thing I was even more afraid I had been all along.

The MRI came to life around me, the hammers and clangs of the vast machine blending with the insistent pounding of the drums in my ears until there was nothing else: just sound, vibrating through my flesh, anchoring itself beneath my sternum. My flesh, my sternum. Ownership was so easy to claim, but did I have any right to it?

Please, please, it's something else, I thought, lying to myself one last time while the option was still open to me. Please, it's not what I think it is. Please, there's another answer

The MRI gave one final pulse as it shut off. The sudden silence was deafening, only slightly lessened by the hum of the automated scanning bed sliding back out into the room, where the chill air raised goose bumps on my arms and legs. I grabbed a lab coat off the side of the machine, pulling it on as I climbed back to my feet. It didn't do much to cut the chill, but I didn't want to spend the time to pick up my clothes.

Nathan was seated at the monitor, the display reflecting off his glasses as he pulled up the first images of my insides. I stopped behind him, putting my hand on his shoulder. He put one of his hands over mine, using the other to continue working the mouse.

My abdomen should have been occupied by a lot of things: organs, scarring, and the pasty white mass of the SymboGen implant, which would naturally gravitate toward the base of my digestive system. It wasn't there. The blood tests had been telling the truth: there was no residual tapeworm protein in my blood because there was no tapeworm in my digestive system. Nathan clicked to the next image. It wasn't in my lungs, either. The image after that proved that my spinal cord was clean.

His fingers tightened on mine. I think that if I had told him to stop then, he would have, and we would both have walked away with the question unanswered. I didn't tell him to stop. I needed to know. He did too, if only so that we would both be standing in the same place for once.

Nathan clicked the mouse. Everything changed.

The image showed the inside of a human skull, normal save for some small remodeling of the bone toward the back. The brain was there, lit up in bright colors that represented activity during the MRI. The tapeworm was there too, showing up as loops of nonreactive white against the bright neural map. It was deeply integrated, slithering in and out of brain tissue. But I'd known that before I'd seen the image, hadn't I? I'd figured it out when I met Adam and Tansy, when I was faced with the reality of their existence. When I'd started to care about them, despite their monstrous origins.

Even knowing what they were hadn't been strictly necessary, had it? Sherman was a tapeworm too, and I had always liked him best, out of all the people at SymboGen. From the moment I'd met him, I'd liked him. If I'd had even the slightest clue that he was a product of Dr. Cale's lab, that would have given me the information I needed. When I met a tapeworm, when I met somebody like me, I liked them. I couldn't help myself. Even if I'd wind up disliking them later, I started from a place of "you are family."

So yes, I'd figured it out, and then I'd locked it away, because I hadn't wanted to admit it to myself. Admitting it would make it real. Only I guess pictures could do the same thing, because I didn't even try to deny that the image on the screen was me.

For the first time in my life, I was looking at who—at what—I really was.

I was never Sally Mitchell after all.

"The protein markers couldn't cross the blood-brain barrier in a detectable form," said Nathan. His voice was soft, like he was afraid anything louder would startle me. He wasn't wrong. "It's why we couldn't detect…" He stopped, obviously unsure how to finish the sentence.

There was no kind way to do it. "Honey, you're not human" isn't a conversation either of us was equipped to have. "Mom was right," I whispered. She'd called me a stranger, and it had hurt, but it hadn't hurt as much as it should have, had it? No, because I'd already figured out the same thing she had: that I wasn't Sally. Her daughter died in the accident that put her in the hospital. I was a stranger living inside her baby's skin. I was a stranger to the entire human race. "Oh, my God. Nathan. Do you see…?"

"It doesn't change anything," he said, suddenly fierce. He let go of my hand as he stood, pushing the chair out of the way before he turned and wrapped his arms around me. He pulled me against him, holding me so tight that I was almost scared he would crush me. I put my arms around him in turn, doing my best to hug him just as hard. Voice still sharp, he said, "Do you understand me? It doesn't change anything."

I raised my head and looked over his shoulder. Dr. Cale had parked her wheelchair in the doorway. She was sitting there watching us, an expression of profound regret on her face. I wouldn't have believed that she was capable of looking so sad, but in that moment, she managed it, and in that moment, she looked like her son. Coloring and race didn't matter, not when stacked up against that expression.

So much of the way she had always interacted with me made sense now. So much of it still needed to be made sense of. "No," I said. "It changes everything." The broken doors that Dr. Cale had spoken of so often were open now; I could no longer pretend that they were just a children's story, something I could safely forget about or ignore.

I looked back to Nathan, raising my eyes to his face and searching for any sign of rejection or revulsion. I didn't want to leave him, but I didn't want to make him stay with me if he couldn't deal with the reality of what I was. I wasn't sure I could deal with the reality of what I was—the calm I was feeling was probably shock, and would pass, replaced by hysteria. Better to make my choices now, when I could trust myself, than to let it wait until I was no longer thinking clearly.

How was I thinking at all? A tapeworm, no matter how cunningly engineered, didn't have the size or complexity to think human-sized thoughts—but I managed it somehow. I had to be… the tapeworm part of me had to be driving Sally Mitchell's brain, using it as storage somehow, like a person uses a computer. The thought made my stomach clench, and so I focused back on Nathan, who was safe; Nathan, who had never known Sally, but had fallen in love with Sal, with me, with the girl who had helped her injured sister into his office. He'd never batted an eye at any of my idiosyncrasies. Sally's family had learned to love me when I replaced their daughter. Nathan had never needed to forget a person I could never be. That had always been so valuable to me. I was starting to understand a little bit more about why.

He met my eyes unflinchingly, and all I saw there was concern, and hope, and yes, love. He looked the same as he always had: black hair, brown eyes behind wire-framed glasses, golden-tan skin, and a serious expression that could spring into a smile at any moment. I didn't see any fear or dismissal, or even dismay, in that face. I blinked.

"You knew," I said, bewildered. "How did you know?"

"I told him." Dr. Cale sounded tired. I pulled away from Nathan and turned to face his mother, who was pale where he was dark, from her sun-deprived skin to the watery blue of her eyes and the ashy blonde of her hair. Her shoulders sagged as she looked at me, and she said, "Back in my lab, when you were asleep on Adam's cot. I thought he should… I'm sorry, Sal, but I thought my son should know that his girlfriend wasn't entirely human. You clearly weren't ready to have the same conversation. Perhaps it was wrong of me."

"I think maybe it wasn't," I said slowly. "I wasn't ready to know this yet. I wasn't letting myself know this yet." I looked down at my hands. "But I was going to figure it out." I had already figured it out, and then locked the knowledge away from myself, as if that sort of thing had ever done any good. Once the signs had been placed in front of me, they had been too easy to follow. I would have followed them again, and maybe then, I wouldn't have been able to make myself forget. "I needed Nathan to know before I did. I needed him to have time to come to terms with it. Because if he'd left me then…"

If Nathan had been having his own freak-out at the same time I was having mine, I don't know how I would have gotten through finding out the truth about myself. Having him pull away from me then—even temporarily—would have devastated me. Here and now, in this lab, with Tansy missing and Sherman alive but suddenly my enemy, losing my humanity was a huge step toward the abyss. Nathan had been able to place himself between me and that long, final fall, and he'd only been able to do it because he'd already known what I was.

Dr. Cale nodded. "I'm glad you see it that way. That's what I was hoping for." She paused, watching me carefully before she continued: "I know you're in shock right now, and I know we've all had a difficult day, but do you think I could have that thumb drive?" She grimaced. "I hate to ask you. I hate to even be here right now. You deserve this moment. But I need that data."

My eyes widened. "I forgot." I had been refusing to give her the thumb drive full of information stolen from the SymboGen computers until she gave me the answers I thought I wanted. But then I'd been distracted by the need for blood tests and MRIs and then… "I'm sorry."

"It's all right." Now the glimmer of a smile touched her lips. "You had other things on your mind."


  • "A riveting near-future medical thriller that reads like the genetically-engineered love child of Robin Cook and Michael Crichton."—John Joseph Adam on Parasite
  • "Readers with strong stomachs will welcome this unusual take on the future."—Kirkus Reviews on Parasite
  • "Fans of [the Newsflesh] series will definitely want to check this new book out. But fans of Michael Crichton-style technothrillers will be equally enthralled: as wild as Grant's premise is, the novel is firmly anchored in real-world science and technology."—Booklist on Parasite
  • "Grant extends the zombie theme of her Newsflesh trilogy to incorporate thoughtful reflections on biomedical issues that are both ominously challenging and eerily plausible. Sally is a complex, compassionate character, well suited to this exploration of trust, uncertainty, and the price of progress."—Publishers Weekly on Parasite
  • "It's a well-grounded medical wariness that gets at the heart of the what the Parasitology series will be asking: What happens when the cure is worse than the disease?"—NPR Books on Parasite
  • "An exceptionally creepy medical-horror thriller that's the perfect spine-tingling read for Halloween...[a] roller coaster ride."—RT Book Reviews on Parasite (4 1/2 stars)
  • "Deft cultural touches, intriguing science, and amped-up action will delight Grant's numerous fans."—Publishers Weekly on Deadline
  • "The zombie novel Robert A. Heinlein might have written."—Sci-Fi Magazine on Feed
  • "A masterpiece of suspense."—Publishers Weekly on Feed (Starred Review)

On Sale
Nov 25, 2014
Page Count
528 pages

Mira Grant

About the Author

Mira Grant lives in California, sleeps with a machete under her bed, and highly suggests you do the same. Mira Grant is the pseudonym of Seanan McGuire — winner of the 2010 John W. Campbell Award for best new writer. Find out more about the author at or follow her on twitter @seananmcguire.

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