During the winter of 1982, the Norwegians were chasing an Alaskan Malamute around the outpost, the pilot was killed when he accidentally dropped a grenade and the passenger was killed by Garry thinking that he was hostile, the crew adopted the dog, Windows tried to contact the outside world, but no luck doing so due to the blizzard. During the night, he was woken up by the fire alarm that was turned on by MacReady, he saw an unknown creature assimilating the dogs, MacReady ordered Childs to bring the flamethrower and ordered him to incinerate it. Windows along with Bennings quarantine the remains of the dog-creature and the Norwegian cadaver in the storage room, but moments after leaving, strands of tentacle-like sinew emerged from the remains of the dog-creature and the Norwegian, and proceed to assimilate Bennings, the Bennings replica was then burned by MacReady. While trying to still contact anyone from the outside, Windows was beaten by Blair who is suffering a mental breakdown, he destroyed the helicopters, tractor and radio with an axe, and killed the remaining sled dogs, containing further contamination. Paranoia quickly sets in as the first attempt to develop a test using uncontaminated blood samples is sabotaged by an unknown party, Windows attempts to break in the weapons deposit to arm himself, but was threatened by Garry, eventually Windows cooperated and let go of the gun.
He and the others begin to suspect MacReady is infected when a scrap of torn shirt containing his name tag is found at the camp, and locked him outside in a severe blizzard. Somehow finding his way back to camp without a guide line, MacReady breaks into a storage room and threatens the rest of the crew with dynamite. In the course of the standoff, Norris suffers a heart attack. When Copper attempts to revive him by defibrillation, Norris' body transforms and bites off Copper's arms and he bleeds to death. Norris' head detaches from his body and the alien uses it in an attempt to escape as the others burn the body, but the head is discovered and incinerated. MacReady proposed a test on everyone to tell who is human and who is a replica. Clark in an act of mutiny tries to stab MacReady with a scalpel, but is quickly shot in the head and killed by MacReady in self-defense. The rest of the crew complies with the test; blood samples are drawn from each member of the team including Copper and Clark and jabbed with a hot wire to see whose blood will react defensively.
Windows is the first to be tested, and upon confirmation that he is indeed human, MacReady arms Windows with a flamethrower to torch anyone who does turn out to be a Thing. Upon realizing that Clark was not infected, Childs denounces MacReady as a murderer, but Macready ignores him. Palmer, the backup pilot, is unmasked as an imitation, and breaks free of it's binds. Unable to get his flamethrower working, MacReady then orders Windows to torch the creature, but Windows froze in fear before he could, allowing the Thing to split its head and used a tentacle appendage to pull Windows into it's jaws head first, and proceeds to violently assimilate him. After it finishes, Macready finally gets the flamethrower working and manages to destroy the Palmer-Thing using a stick of dynamite and then torches the now partially assimilated Windows.
- In the film's original script, Windows was instead named Sanchez, and in the novelization, his name is Sanders.
- There was an alternate storyboarded scene that was planned for Windows' demise. It is similar to his death in the novel. Windows trying to escape from the Thing is attacked and dragged away to his death. Interestingly enough, the script has Windows biting down on a cyanide capsule just before he is engulfed by the Thing.
- Windows had been accused (esp. after going for the shotgun rack out of panic) of going into the blood bank and sabotaging it for the serum test. Assuming Garry was honest in not having used the station keys he wears on his ring for that, no one human had done it-but in fact The Thing, most likely Palmer. At the time when Blair is destroying the radio, if you look over the characters that are present, Palmer is nowhere to be seen. The blood supply would have had to be destroyed shortly before Blair was taken to the tool shed so it had to be when Blair was destroying the radio. Therefore Palmer was most likely The Thing that sabotaged the blood supply. Windows gets the keys from Garry and when he returns, he drops them after seeing Bennings getting assimilated. Bennings must have hid the keys for another member to take and use at will.
- According to producer Stuart Cohen, fans who picked up on Windows dropping the keys are correct. The production team even lifted the sound of the keys hitting the floor in post-production for emphasis. This is how Garry's keys were lost, then either Bennings hid them quickly, or one of the other Things (Norris or Palmer) found the keys when they went back to search the room, then pocketed them before anyone could notice. Note that Windows looks visibly upset when Garry explains that he only gives the keys to Copper when he needs them, but suggests someone might have stolen them: Windows knows its actually his fault the alien got the keys, but he doesn't want to openly admit that he was the last known person with the keys, as this would make everyone else start to suspect him (as we find out in the later blood-test that Windows was always human).