All irregularities will be handled by the forces controlling each dimension. Transuranic heavy elements may only be used where there is no life. Heavy atomic weights are available: Arsenic, Caesium, Francium, Lead, Mercury, Plutonium, Radon, and Uranium.

Arsenic has been assigned.

MacReady's flask was empty. It had been for hours, maybe minutes, since Childs drained the last of it. Had Childs changed his jacket? It didn't matter now. A condemned man got a last drink.

The flamethrower was virtually empty. One shot left, or they'd both freeze, which could be what Childs wanted because only MacReady would really die. If he could get back to his sleeping bag he had a torch, a flare, in it but if he went for them he'd give Childs the chance to kill him. Unless Childs was human. How could he tell? He could see his own breath in the cold, but was Childs' breath gusting? He started to laugh. He started to laugh because it didn't matter anyway, because everything had been for nothing. It didn't matter that he'd burned the base, it didn't matter that Childs might be a thing. It didn't matter that he was probably going insane from cold and exposure.

It didn't matter at all because in the storm and the cold there was another person walking towards them.

Another human, almost certainly another thing. He only had one shot.

"The hell?" Childs looked as shocked as a person would be. Maybe he was human. It didn't matter. MacReady climbed to his feet, wearily stretching fingers he couldn't feel any more inside his gloves. They just had to work well enough to pull a trigger. The figure stopped.

"Stay back." A woman's voice. There weren't any women on the team, unless the thing was impersonating one of the Norwegians. He halted, as Childs did. If she wouldn't let them close it argued for her being human, or for seeing the flamethrower and trying to get their guard down.

Or she was a rescuer, and the Childs-thing was about to escape. He brought the flamethrower up, realised he couldn't cover both her and Childs, and swung it back to Childs as the man shouted.

"You with the rescue team?"

"A rescue team has been dispatched. The helicopter will arrive in one hour." Her voice was precise, accented in a way he hadn't heard before. English as a second language.

"We can't be on it." MacReady's throat hurt from the cold, and his voice cracked from fatigue, but that fact hadn't changed.

"Can't let this get out." Childs agreed, and that was a first, "but the blood test. We do the blood test, find out who's human-" Childs took a few paces towards her and she jumped back athletically, feet landing unerringly in the snow.

"Do not approach." The warning was clear in her voice, and he stopped. Silver glinted in her pocket, frosted with ice. If she had a gun it was a pointless threat. At forty below the mechanism would be frozen solid.

"There's nothing to do the test with." MacReady gestured to the ruins with the flamethrower, not caring how Childs took it. It didn't matter if they were human, he couldn't be sure they would stay that way.

The narrative has been taken without permission. Report any sightings.

"So we got no way to prove we're human?" Childs slumped. She shook her head, not lowering the eyes that glinted darkly under the parka hood. Childs shook his head, smiling without humour as the situation dawned on him. "What about you? Who the hell are you?"

"I am called Miss. Jackson. You would not be familiar with my organisation." MacReady swore. Some government must've found out what happened, got half the story and wanted the damn thing as a weapon. He couldn't let that happen. If it got out, humanity was dead.

"So what're you here for?" MacReady asked uninterested, knowing the answer. He just had to get a clear shot on her and Childs. Had to make his last shot count. She lowered the parka hood, showing neat rows of cornrows above the high forehead, frosted at the front with snow.

"I was sent here to ensure it did not escape." There were ice trails glistening on her cheeks, frozen tear tracks. The base must have got to her, all the bodies. If she was still human.

"Damn good trick when no one knows we're here," Childs growled. How the hell was he so lively when MacReady was ready to drop?

"You missed Blair's radio. It was easier to create than his transport vessel, so it was built first. He signalled the shore for aid." He cursed, coming to his feet and heard Childs do the same. "The rescue helicopter was dispatched and, due to the danger to humanity, so was I." Blair would never have said anything about a danger to humanity. Was she lying? Had one of the Norwegians got a message out?

"Then you got to turn them back!" Childs shouted. "You saw what happened here."

"I have already swept the base and made it safe." Her face was calm but another tear began to fall. "Forgive me. It is the first time I have found something alive to speak to." Rescue had to be a fucking awful job, if you were a human doing it. She had to be lying, because anything that had swept the base would have been infected.

"You can't be sure it's gone," MacReady said in exhaustion, knowing what he had to do. "I burned the base, and then he walked out of the storm."

"Me? You saying I'm the fucking thing?" Childs turned on him.

"I know I'm me." MacReady rebutted, frozen tongue sticking to his teeth. "Don't know shit about you."

"Yeah, so you say."

"I burned the thing." The tip of the flamethrower waved wildly around the ruins of the base.

"Yeah, covering your own tracks. Leave a pretty looking human corpse no one will look twice at."

"That your plan, Childs? Glad you shared it."

"I passed the blood test," Childs said into his face, and then turned away sharply and raised his voice. "Hey, lady I passed the blood test, ask about his, eh? He goes off alone with Gary and Niuls and then only he comes back."

"Are you saying I-"

"I'm saying you murdered them like you did Clark."

"You son of a -" MacReady froze, his clenched fist pulled back to punch. What was he thinking? Hit it, get it on his gloves, split his knuckles in the cold, get infected. Carefully he backed away, swinging the flamethrower back to ready position.

"You got a radio, lady?" he asked, and she shook her head slowly.

"One is not required for my duty."

"Your duty? Fuck your duty," Childs said, bitterly, staring down the flamethrower barrel. "What good are you anyway?"

"I am good at problem solving. I had hoped that something that could speak would negotiate." She looked at Childs for a long moment and Childs started to laugh.

"Can't negotiate with that." Childs rubbed a forehead that had turned dull and grey in patches where frostbite was setting in. MacReady scowled. It really didn't know when to drop the pretence, or it was trying to get the drop on both of them. He had to agree with the statement.

"Not a chance, sweetheart, it will just eat you." She looked from one to the other of them and then sighed and nodded once. Just once.

"I understand."

"Good, then warn the fucking rescue team off," MacReady said.

"There's no need. The base is safe. They will not be infected."

"You can't possibly know that," Childs scoffed. "Not like there's any way of detecting the damn thing."

"Yes. There is." Her fingers tightened round the silvered metal in her pocket. MacReady blinked frosted eyes clear. A detector? That changed everything.

"Then which of us is-" Childs demanded wildly.

"Me, him?" MacReady spoke over him.

"Neither of us?" Child's voice broke with sudden hope.

"I am so very sorry," she said quietly, as their voices quieted in expectation. She lowered her hand from her pocket. A silver circlet glittered with frost in her gloved fingers.

"Both." She took a step forward and was alone in the ruins.