Karen began to take off her clothes in a matter-of-fact way. Rick Hutter wasn’t sure what to do; he felt embarrassed to be looking at Karen while she undressed, more embarrassed to be swimming with her and Erika naked. He got his clothes off fast, and jumped into the water.

“Welcome to Eden,” Erika said.

“A dangerous Eden.” Rick ducked down, and began scrubbing his head.

As Karen explored the pool, she saw it was like a fish tank full of living things, but they weren’t fish, they were single-celled organisms. The creatures spun and darted and drifted. A torpedo-shaped creature swam up against her.

It was a Paramecium, a pond-water animal, a protozoan consisting of a single cell. The Paramecium was covered with rippling hairs that propelled the creature through the water. It began bumping along Karen’s arm, tickling her skin. She cupped her hands and picked up the Paramecium, holding it in a handful of water. She could feel the hairs beating on her palms, and the cell squirmed. It reminded her of a cat that didn’t like being held. “I won’t hurt you,” she said to the cell, stroking it gently with a fingertip. As she touched the hairs, they reacted by reversing direction, beating against her finger. It was like stroking velvet that fought back.

Why am I talking to a cell? Karen thought. That’s pretty silly. A cell is a machine, she told herself. It’s just a clockwork of proteins inside a water-filled bag. And yet…she couldn’t help feeling that the cell was also a small being, full of its own purposes and desires. A cell wasn’t intelligent the way a human is, of course. A cell couldn’t imagine galaxies or compose a symphony, yet it was a sophisticated biological system, perfectly adapted to survive in this environment, and bent on making copies of itself, as many as possible. “Good luck,” she said out loud, opening her hands and letting the cell go free. She watched it hurry away, corkscrewing as it swam. She said to Rick, “We’re not so different from these protozoa.”

“I don’t see the resemblance,” Rick said.

“A person is a protozoan on the day the person is conceived. As the biologist John Tyler Bonner likes to say, ‘A human being is a single-celled organism with a complicated fruiting body.’ ”

Rick grinned. “The fruiting body is the best part.”

“Crude,” Karen remarked. Erika smirked at him.

A shadow crossed the pool, and a scream echoed above. Instinctively they ducked their heads under the water. When they came up, Rick looked around and said, “Birds.”

“What kind?” Karen said.

“No idea. They’re gone, anyway.” They washed their clothes in the pool, rinsing the dust and mud out. Afterward, they spread their clothes to dry, and sunbathed for a little while on the moss. The clothes dried quickly.

“We need to get going,” Rick Hutter said, buttoning his shirt.

Just then, the distant cries grew louder, and dark shapes flashed through the air above them. The humans leaped to their feet.

A flock of birds was cruising along the cliffs, landing and taking off. The birds were foraging. Their cries shattered the air.

A bird landed before them. It was enormous, with shiny black feathers, a yellow bill, and an alert gaze. It hopped around, investigating the spot, and screamed, a raspy, echoing cry. And then suddenly it took off. More birds arrived overhead, and they began circling, inspecting the scene, and landing in trees that clung to the cliff face. The humans became aware of many eyes watching them. The cries of the birds surrounded the pool.

Rick dashed for the truck, grabbed the gas rifle. “They’re mynahs!” he shouted. “Get cover!”

Mynahs were carnivores.

Danny had tumbled out of the truck, and he cowered underneath it. Karen had thrown herself down behind a rock, while Erika wedged herself down into clumps of moss. Rick knelt in the open, holding the gas rifle, watching the black shapes as they swept past the cliff, their cries streaming in the wind.

The birds saw him. They had no fear of something so small. A mynah cruised in and landed, and hopped across the ground toward him. He fired at the bird. The gun erupted with a hiss, kicking him backward, but at that instant the mynah leaped into the air and soared away, downwind. He had missed. He reloaded frantically, slamming another pin into the chamber. The gun was a bolt-action rifle: it fired one projectile at a time.

He thought there must be twenty or thirty of them, anyway. They swirled around the cliffs, their cries deafening. “They hunt in packs,” Rick said.

Another mynah landed.

He pulled the trigger. Nothing happened.

“Shit!”

A jam. He frantically worked the bolt. The bird took one hop toward him and cocked an eye at him. Then it pecked at him, and grabbed the gun. It was a shiny object; it had attracted the bird’s eye. The mynah slammed the gun against a rock, crumpling it, and tossed it aside. Then it held up its head, opened its beak, and howled, letting out a cry that seemed to make the ground shake.

Rick, meanwhile, had thrown himself flat, and was crawling for the harpoon, which lay near the pool.

The mynah turned its attention to Erika, who cowered in the moss. She crouched, staring up at the bird, and suddenly lost her nerve. She broke and ran, ducking her head, whimpering.

“Don’t, Erika!” Rick shouted at her.

Erika’s motion drew the bird’s attention, and it hopped toward her.

Karen King had been watching, and she made a sudden decision. She would sacrifice her life for Erika. She would give Erika a chance to live. It was good while it lasted, she thought, and stood up and ran toward the bird, waving her arms. “Hey! Take me!”

The bird swerved, and pecked at Karen, but missed her, and she went sprawling. Erika had now jumped into the truck and was attempting to start it. Erika had gone into a full-blown panic; she didn’t know what she was doing, other than trying to get away. Danny shouted at her, “Stop! I order you to stop!” Erika paid no attention. The truck lurched off, and began climbing upward along the rocks. But it was very exposed.

She was deserting the others.

“Erika! Turn around!” Karen screamed.

Erika had gone past the point of hearing anybody.

The truck, shiny and moving up the cliff, its six legs working, must have seemed like something tasty or interesting. A mynah coasted in and plucked Erika out of the driver’s seat. Packs and gear flew out of the truck as it tumbled down the cliff and bounced out into sheer air. And then it was gone.

The mynah landed, carrying Erika Moll in its beak. The bird slammed her several times against the cliff, whipping its head back and forth to kill its prey. The bird then took off, carrying the corpse. Immediately it got into a squabble with another mynah, and they fought with each other over the remains of Erika Moll, and tore the body apart in midair.

It wasn’t over. Rick had gotten his hands on the harpoon, and he looked around: where was Karen? She was lying on the ground, out in the open, underneath a mynah. The bird, which had an unusual black streak on its bill, had landed, and was staring down at Karen. It seemed to be trying to make up its mind about her. Was this thing edible?

“Karen!” Rick shouted, and threw the harpoon at the bird.

The harpoon, a thread of metal, went into the bird’s feathers. Not very far. The bird shook itself, and the harpoon dropped to the ground. The bird studied Karen.

She crouched, trying to make herself look small and unappetizing.

“Over here!” Rick shouted, and started running, hoping to distract the bird.

“No, Rick!”

The mynah cocked its eye at Karen when she spoke. It lunged for her and picked her up in its beak, threw its head back, and swallowed Karen in one gulp. Then it flew off, wings thundering.

“Damn you!” Rick yelled at the mynah. He waved the harpoon at the bird, which had become a fluttering speck in the distance. “Come back with her!” The flock in the trees chattered and roared. Now he couldn’t tell which of them had eaten Karen. “Come back! Come back for a fair fight!” He jumped up and down, waving his arms, shaking the harpoon.