“Who is it?” the robot door demanded shrilly.

“Commander Morrison orders this man put under the Captain’s care.”

There was a hesitant pause, then: “The Captain is busy.”

“This is an emergency.”

The robot’s relays clicked while it made up its mind. “The Commander sent you?”

“Yes. Open up.”

“You may enter,” the robot conceded finally. It drew its locks back, releasing the door.

The guard pushed the door open. And stopped.

On the floor lay Captain Taylor, his face blue, his eyes gaping. Only his head and feet was visible. A red-and-white scatter rug was wrapped around him, squeezing, straining tighter and tighter.

Hall dropped to the floor and pulled at the rug. “Hurry!” he barked. “Grab it!”

The three of them pulled together. The rug resisted.

“Help,” Taylor cried weakly.

“We’re trying!” They tugged frantically. At last the rug came away in their hands. It flopped off rapidly toward the open door. One of the guards blasted it.

Hall ran to the vidscreen and shakily dialed the Commander’s emergency number.

Her face appeared on the screen.

“See!” he gasped.

She stared past him to Taylor lying on the floor, the two guards kneeling beside him, their blasters still out.

“What—what happened?”

“A rug attacked him.” Hall grinned without amusement. “Now who’s crazy?”

“We’ll send a guard unit down.” She blinked. “Right away. But how—”

“Tell them to have their blasters ready. And better make that a general alarm to everyone.”

Hall placed four items on Commander Morrison’s desk: a microscope, a towel, a metal belt, and a small red-and-white rug.

She edged away nervously. “Major, are you sure—?”

“They’re all right, now. That’s the strangest part. This towel. A few hours ago it tried to kill me. I got away by blasting it to particles. But here it is, back again. The way it always was. Harmless.

Captain Taylor fingered the red-and-white rug warily. “That’s my rug. I brought it from Terra. My wife gave it to me. I—I trusted it completely.”

They all looked at each other.

“We blasted the rug, too,” Hall pointed out.

There was silence.

“Then what was it that attacked me?” Captain Taylor asked. “If it wasn’t this rug?”

“It looked like this rug,” Hall said slowly. “And what attacked me looked like this towel.”

Commander Morrison held up the towel to the light. “It’s just an ordinary towel! It couldn’t have attacked you.”

“Of course not,” Hall agreed. “We’ve put these objects through all the tests we can think of. They’re just what they’re supposed to be, all elements unchanged. Perfectly stable non-organic objects. It’s impossible that any of these could have come to life and attacked us.”

“But something did.” Taylor said. “Something attacked me. And it if wasn’t this rug, what was it?”

Lieutenant Dodds felt around on the dresser for his gloves. He was in a hurry. The whole unit had been called to emergency assembly.

“Where did I—?” he murmured. “What the hell!”

For on the bed were two pair of identical gloves, side by side.

Dodds frowned, scratching his head. How could it be? He owned only one pair. The others must be somebody else’s. Bob Wesley had been in the night before, playing cards. Maybe he had left them.

The vidscreen flashed again. “All personnel, report at once. All personnel, report at once. Emergency assembly of all personnel.”

“All right!” Dodds said impatiently. He grabbed up one of the pairs of gloves, sliding them onto his hands.

As soon as they were in place, the gloves carried his hands down to his waist. They clamped his fingers over the butt of his gun, lifting it from the holster.

“I’ll be damned,” Dodds said. The gloves brought the blast gun up, pointing it at his chest.

The fingers squeezed. There was a roar. Half of Dodd’s chest dissolved. What was left of him fell slowly to the floor, the mouth still open in amazement.

Corporal Tenner hurried across the ground toward the main building as soon as he heard the wail of the emergency alarm.

At the entrance to the building he stopped to take off his metal-cleated boots. Then he frowned. By the door were two safety mats instead of one.

Well, it didn’t matter. They were both the same. He stepped onto one of the mats and waited. The surface of the mat sent a flow of high-frequency current through his feet and legs, killing any spores or seeds that might have clung to him while he was outside.

He passed on into the building.

A moment later Lieutenant Fulton hurried up to the door. He yanked off his hiking boots and stepped onto the first mat he saw.

The mat folded over his feet.

“Hey,” Fulton cried. “Let go!”

He tried to pull his feet loose, but the mat refused to let go. Fulton became scared. He drew his gun, but he didn’t care to fire at his own feet.

“Help!” he shouted.

Two soldiers came running up. “What’s the matter, Lieutenant?”

“Get this damn thing off me.”

The soldiers began to laugh.

“It’s no joke,” Fulton said, his face suddenly white. “It’s breaking my feet! It’s—”

He began to scream. The soldiers grabbed frantically at the mat. Fulton fell, rolling and twisting, still screaming. At last the soldiers managed to get a corner of the mat loose from his feet.

Fulton’s feet were gone. Nothing but limp bone remained, already half dissolved.

“Now we know,” Hall said grimly. “It’s a form of organic life.” Commander Morrison turned to Corporal Tenner. “You saw two mats when you came into the building?”

“Yes, Commander. Two. I stepped on—on one of them. And came in.”

“You were lucky. You stepped on the right one.”

“We’ve got to be careful,” Hall said. “We’ve got to watch for duplicates. Apparantly it, whatever it is, imitates objects it finds. Like a chameleon. Camouflage.”

“Two,” Stella Morrison murmured, looking at the two vases of flowers, one at each end of her desk. “It’s going to be hard to tell. Two towels, two vases, two chairs. There may be whole rows of things that are all right. All multiples legitimate except one.”

“That’s the trouble. I didn’t notice anything unusual in the lab. There’s nothing odd about another microscope. It blended right in.”

The Commander drew away from the identical vases of flowers. “How about those? Maybe one is—whatever they are.”

“There’s two of a lot of things. Natural pairs. Two boots. Clothing. Furniture. I didn’t notice that extra chair in my room. Equipment. It’ll be impossible to be sure. And sometimes—”

The vidscreen lit. Vice-Commander Wood’s features formed. “Stella, another casualty.”

“Who is it this time?”

“An officer dissolved. All but a few buttons and his blast pistol—Lieutenant Dodds.”

“That makes three,” Commander Morrison said.

“If it’s organic, there ought to be some way we can destroy it,” Hall muttered. “We’ve already blasted a few, apparently killed them. They can be hurt! But we don’t know how many more there are. We’ve destroyed five or six. Maybe it’s an infinitely divisible substance. Some kind of protoplasm.”

“And meanwhile—?”

“Meanwhile we’re all at its mercy. Or their mercy. It’s our lethal life form, all right. That explains why we found everything else harmless. Nothing could compete with a form like this. We have mimic forms of our own, of course. Insects, plants. And there’s the twisty slug on Venus. But nothing that goes this far.”

“It can be killed, though. You said so yourself. That means we have a chance.”

“If it can be found.” Hall looked around the room. Two walking capes hung by the door. Had there been two a moment before?