The question was: Why?

She knew that whoever was in charge wouldn’t allow the products of his or her experiments to run free, not when those products could talk and think for themselves. She assumed the only reason that the girl and boy, the replicas, hadn’t been found and taken into custody already was because of all the chaos. Probably they were still counting the dead and the missing. Staying on the marshes for any length of time was a huge risk. But Gemma sensed that the clones weren’t ready to move yet, and she knew that she had to stay close to them, that the ember of truth was here, with them. She needed time to think and to plan.

She expected more resistance from Jake. But he only shook his head and said, “We should try and get some sleep. We’ll want to get off the marshes as soon as possible.” And the clones didn’t argue anymore. They obviously didn’t want to be too far from the food and water.

They moved to the far side of a contorted thicket of mangrove trees that blocked them from a view of the body. Gemma didn’t want to camp so close to the dead girl. She couldn’t stand to think of her, that face like her face hollowed out by hunger, the hair that Gemma sweated and toiled to keep straight shaved close to her fragile scalp. She had never been superstitious, but it felt like a bad omen, as if the fate of her double might wear off on her.

On the other hand, she didn’t want to go far in the darkness, and the girl and the boy, the replicas, were exhausted. The replicas bedded down side by side, although Gemma noticed that they hardly spoke or even acknowledged each other. As if they each belonged two separate realities that only coexisted momentarily.

Jake fell asleep right away, using a rolled-up towel as a pillow and clutching his backpack as though it were a teddy bear. Gemma, however, lay awake long after even the replicas had fallen asleep. It wasn’t just because she was physically uncomfortable—she was clammy and too hot; the whine of mosquitoes needled her; the ground was uneven and unpleasantly spongy; she was dirty and she was sure that she smelled—but because of an itchy, hard-to-name feeling inside, like the wriggling of thousands of ants under her skin, in her blood and her veins. She imagined the girl on the other side of the trees, the second-Gemma, coming to life again, slithering through the mud, reaching for Gemma’s face with bloodied fingernails, reaching for Gemma’s hair, demanding it back. . . . She had to sit up, stifling a cry of terror.

Someone had cloned her. It was the only explanation that made sense, but she couldn’t accept it. Had her father known? Was that why he had left Fine & Ives, and ruptured forever with his business partner? Was that why he’d wanted Haven shut down? A scientist had taken a sample of Gemma’s DNA when she was a baby and used it to make another Gemma. Except . . .

The dead girl wasn’t just another Gemma. She had Gemma’s DNA, her face and her freckles, but even now her insides were liquefying, her stomach bloating with gases. She’d had a different name, different memories and preferences, and a very different life. Two people built of the same material, but radically separated by experience and now by death.

Had her father known? Or had he only suspected?

Maybe during one of her many hospital stays as a baby, someone had stolen some tissue from her without her parents’ knowledge. That must be it. There would have to be a black market for things like this, places on the internet you could go to buy kiddie porn and new livers and medical samples.

She knew that was nonsensical, though. What were the chances that her DNA had randomly ended up in the same research institute her father’s company had helped fund?

She would never sleep. How could she, with that dead girl, that doubled girl, so close by? So many thoughts were turning in her head, she felt dizzy. She had to know. She had to understand this place, and what her father’s connection to it had been. What her connection to it was.

It was much harder to get into the kayak without Jake there to steady her, and again she had a fear of turning over and getting stuck, like a banana in a too-tight skin. But she managed it eventually and, after flailing around with the paddle for a bit, loosed herself from the tangle of long grass and reeds and maneuvered into the dark, glassy water. She didn’t even know how to read a compass, even though her phone must have had one. But she felt confident that she was sufficiently close to the island that she wouldn’t get lost, and she even had the idea of tying her sweatshirt to the overhanging branches of one of the mangrove trees, so that she would be able to find her way back.

After only a few minutes, she regretted the decision. Paddling was much harder than Jake had made it look. Her heart was soon thumping and her shoulders ached. And she had to keep angling into the shadows and sloshing onto miniature pockets of land to orient herself. Down in the water she could see nothing, not with the mangroves crowding her and the reeds tall and spindly and white as bone. After a little while, the water became scummy with a fine layer of trash from the island, not just ash but human things, old buttons and charred plastic pieces and even bits of paper. She found a laminated ID entangled among the reeds: the picture showed a grim-faced black woman and indicated low-security clearance. She pocketed it. Now the thudding of her heart had nothing to do with the effort of paddling.

She came around a bend and sucked in a sharp breath: there beyond another stretch of muddy water was the fence, and empty guard towers, and trees blackened by fire beyond it. She must still be on the side of the island that had never been developed, because she could see only one long building through the trees, a shed or a storehouse that appeared abandoned. She dragged the kayak onto the shore and set out through the reeds down the narrow beach, as frogs splashed noisily into the water to avoid her, keeping very low to the ground in case there were still soldiers patrolling.