Who Goes There?

This science fiction novella is set at a remote Antarctic research camp where 37 men are stationed for a scientific expedition. Cut off from civilization by extreme cold, the camp becomes the site of a crisis unlike anything its members have prepared for.

Commander Garry, the expedition leader, assembles the personnel in the Administration Building, where a tarpaulin-wrapped object drips on the table, giving off a faint alien odor. Garry calls on McReady, the expedition's bronze-bearded meteorologist and second-in-command, to explain. McReady recounts how a Secondary Magnetic Pole Expedition traveled 80 miles southwest to investigate a magnetic anomaly too powerful for any known material. They found a spacecraft entombed in ice. McReady theorizes that roughly 20 million years ago, the ship descended from space, became entangled with Earth's magnetic field, struck a granite ridge, and crashed. One passenger stepped out and froze within 10 feet of the wreck. When the team dug toward the ship, Barclay, the camp mechanician, accidentally struck the frozen creature's skull with an ice-ax. Blair, the expedition's biologist, and Dr. Copper, the camp physician, cut the creature out in a block of ice. The team attempted to enter the ship, but a thermite bomb intended to soften ice inside the lock ignited the magnesium-alloy hull, destroying the vessel and what appeared to be three other frozen passengers.

A fierce debate erupts over the recovered specimen. Blair insists it must be thawed for study, arguing the find is irreplaceable. Norris, the expedition's physicist, opposes thawing, fearing unknown diseases and admitting the creature has given him nightmares in which it could change shape and imitate a man. When the tarpaulin is pulled back, the men see three blazing red eyes, a face ringed with writhing blue tendrils, and the broken ice-ax haft lodged in its skull. Half the company flees in horror. Garry sides with Blair, and the creature is left to thaw overnight in the Cosmos House cosmic-ray shack, with Connant, the cosmic-ray physicist, standing watch.

Blair assures everyone the creature is too complex to revive. Alone with the thawing body, Connant notices the red eyes are no longer sightless and tentacular things pulse from its neck, but he fails to react. The creature escapes. A wild howl erupts from Dogtown, the area where sled dogs are kept: The creature has stumbled among the huskies, which break their chains and attack. Connant fires on it with a revolver, but the creature keeps fighting. McReady arrives with a blowtorch, and Barclay rigs an electrocution device charged with 220 volts. When Barclay jabs the device into the creature, it screams, collapses, and the dogs tear it apart.

Blair examines the remains and delivers a terrifying explanation. The creature had begun absorbing and imitating Charnauk, one of the sled dogs. Its protoplasm can study and replicate the cells of any organism it digests, controlled by specialized nuclei that reshape its tissue into perfect copies. The creature does not reproduce; it becomes what it absorbs, retaining surplus mass to imitate additional organisms. It has no natural enemies because it becomes whatever threatens it. If it reached civilization, it could replace the entire human population. Blair reveals he has already smashed every airplane magneto in camp to prevent the creature's escape. He collapses, laughing and crying, and Dr. Copper sedates him. Delirious, Blair asks whether Connant is really Connant, pointing out that the creature wanted to be a man, not a dog.

Suspicion falls on Connant. Dr. Copper proposes a serum test: Injecting human blood into a dog over several days will make the dog's serum react to human blood but not to alien tissue. Garry and Copper volunteer their own blood. Connant is confined, and Blair is transported to East Cache, a remote shack two miles from camp. McReady institutes a rule requiring movement in groups of four. Norris raises the disturbing possibility that the creature can read minds, a fear supported by Blair's account of telepathic dreams from the creature.

After six days, Copper performs the test. Connant's blood produces the expected reaction, seemingly proving he is human. Moments later, tissue from the dead monster also triggers a reaction, meaning one of the two blood donors, Garry or Copper, is a monster. The test is invalidated. McReady sedates the hysterical Copper and assumes command. He tests his own blood to confirm Garry and Copper are not both monsters, but the test cannot distinguish which one is the creature. McReady tests the camp's animals and discovers every dog and cow has been replaced except the one immune dog. With no animals remaining, the creature must focus entirely on replacing humans.

The camp operates under rotation sleeping. Kinner, the scar-faced cook, now hysterical, is moved to Cosmos House, where he shrieks prayers and hymns ceaselessly. McReady quietly develops a new test but keeps it secret, aware the creature can read minds. During a movie screening, Kinner's screaming stops. McReady finds him with a knife in his throat. The knife is traced to Clark, the dog handler, who slips out during the film to kill what he believes is a monster. When McReady tests the corpse with the electrocution device, it begins to change, sprouting scaly fur and clawed talons. The Kinner-thing had been a monster all along, its hours of prayer a flawless performance. Clark is confirmed human, since a monster would not kill one of its own kind.

McReady announces his definitive test. Because every part of the creature is an independent, self-preserving organism, a sample of monster blood will try to escape a threat such as a heated wire, while human blood will simply char. He draws blood from each man and touches it with a heated platinum wire. Van Wall, the chief pilot, is confirmed human. Barclay is next, also human. When McReady calls Dutton, a crew member standing guard over the power connection, the blood exposes him as a monster, and the men destroy the creature. Connant and Commander Garry are also revealed as monsters and destroyed. In total, 14 of the 37 men prove to be imitations.

McReady orders all remains incinerated, then remembers Blair, isolated in East Cache for over a week. McReady, Van Wall, Barclay, and Norris ski to the shack, where they find no chimney smoke but a fierce blue light and the sound of frantic toolwork. The thing inside is no longer Blair. When the men smash through the door, a blue, rubber-ball-like creature bounces up, wielding a gleaming metal weapon. Norris destroys the weapon and the creature's eyes with his revolver. McReady drives the blinded creature outside with a blowtorch until it is reduced to a glowing coal.

Inside the shack, they discover the Blair-thing built an atomic power generator and a nearly completed anti-gravity harness from scavenged parts. Barclay straps on the harness and floats across the room, confirming it works. Norris explains the stakes: Another half hour and the Blair-thing would have leaped to America and begun replacing the world's population. With atomic power and anti-gravity, it could have reached other planets. McReady reflects that only by this narrow margin have they saved humanity and the solar system from invaders who came from a world orbiting a brighter, bluer sun beyond the stars.