The scene is a distant Arctic research station, where a UFO has crashed. The investigating scientists discover that the circular craft has melted its way into the ice, which has frozen up again.
While attempting to recover the ship, Captain Patrick Hendry (Kenneth Tobey) accidentally explodes the vessel, but the pilot -- at least, what seems to be the pilot -- remains frozen in a block of ice. The body is taken to base headquarters, where it is inadvertently thawed out by an electric blanket.
The alien attacks the soldier guarding him and escapes into the snowy wastes. An attack dog rips off the alien's arm, whereupon Dr. Carrington (Robert Cornthwaite) discerns that The Thing (played by future Gunsmoke star James Arness!) is not animal but a member of the carrot family, subsisting on blood.
While the misguided Carrington attempts to spawn baby Things with the severed arm, the parent creature wreaks murderous havoc all over the base. Female scientist Nikki (Margaret Sheridan) suggests that the best way to destroy a vegetable is to cook it.
Over the protests of Carrington, who wants to reason with the visitor (a very foolhardy notion, as it turns out), the soldiers devise a devious method for stopping The Thing once and for all.
This oversimplification of The Thing does not do full justice to the overall mood and tension of the piece, nor does it convey the lifelike business as usual approach taken by the residents of the military base in dealing with something beyond their understanding. A superior blend of science fiction, horror, naturalistic dialogue, and flesh-and-blood characterizations, The Thing is a model of its kind.