During the winter of 1982, a group of Norwegians chased a shape-shifting extraterrestrial organism (imitating an Alaskan Malamute) from their ruined research station to U.S. Outpost 31. After the Norwegians get themselves killed and accidentally destroy their helicopter, Norris and others rush to extinguish the blaze. The men carry the Norwegian to the rec room. Several hours later, as evening fell, Dr. Copper and helicopter pilot R.J. MacReady return from their investigation of the Norwegian camp with the charred remains of a split-faced creature - which all present, including Norris, stare at in disgust. During the night, the men were awoke by the building's fire alarm, triggered by MacReady after hearing the disturbance in the dog kennels. One of the first to arrive at the kennels with MacReady, Norris witnesses the dog-thing assimilating the outpost's sled dogs. The creature is incinerated by Childs and its remains (following an autopsy) are temporarily put into storage, during the moving of which Bennings is assimilated. Norris, along with the other men, is drawn outside by the discovery of a half-assimilated Bennings, who is also promptly incinerated.
Mid-way through the film, Norris assists the other men in overpowering a revolver-wielding Blair, who has destroyed the outpost's helicopter, snowcat, radio and killed the remaining sled dogs, under the pretences of preventing the Thing from escaping. After Copper, Childs, Fuchs and MacReady lock him in the tool shed, Copper returns to the infirmary to find the blood locker has been opened by key and its contents destroyed - preventing a possible blood serum test. At the doctor's beckon, Norris and the others arrive and paranoia breaks out amongst the men as Garry and Copper are accused of sabotaging the supplies. His authority shattered beyond repair, Garry decides to hand over his revolver and leadership to someone else - first offering it to Norris, only for the researcher to refuse the offer. As MacReady takes command of the group, he orders Norris to incarcerate Garry, Copper and Clark in the rec room - tying them to the couch and drugging them with morphine.
After Fuchs goes missing during a deliberate power outage, MacReady organizes a search party and orders Norris to stay behind with the suspects in the rec room; telling him to incinerate them if they move and to trigger the alarms if anything suspicious occurs. After approximately forty minutes has elapsed, the men begin to suspect that something has happened to MacReady and Nauls whilst investigating his shack and they begin to barricade the doors. It is at this point that Norris begins to show symptoms of discomfort whilst moving equipment to the supply room. Looking out the window he notices Nauls making his way back to the entrance and they let the man in. After Nauls explains that he cut MacReady loose after discovering a scrap of torn clothing containing his name tag, the men begin to suspect the pilot of being an imposter and lock him outside in a severe blizzard. Somehow finding his way back to camp without a guide line, MacReady breaks into the storage room and threatens the rest of the crew with dynamite. In the course of the stand-off, Norris and Nauls unsuccessfully attack Macready from behind, causing Norris to apparently suffer a heart attack. When Copper attempts to revive him by defibrillation, Norris reveals himself as an imitation and kills Copper before he is subsequently incinerated.
- The infamous "Defibrillator scene" in which Norris is exposed and Copper is killed never actually happened in the short story Who Goes There?. In fact, not only does Norris survive but he says the final lines.
- In the scene where the dog enters the living quarters and claims its first victim, a shadow can be seen on the wall. Since the film's release, fans have speculated this to be either Palmer or Norris (inconclusively, due to the ambiguous nature of the scene). According to producer Stuart Cohen, the individual was intended to be Palmer. At the time of filming actor David Clennon's silhouette was considered too distinct, and after failed attempts to soften the edges to diffuse the image, director John Carpenter used stunt coordinator Dick Warlock's outline to throw viewers off the scent.
- Norris was probably assimilated by Palmer off screen.