- "You gotta be fucking kidding..."
- ― Palmer after witnessing the Head Spider
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. Palmer is one of the first men to encounter the Norwegians, who accidentally destroy their own helicopter; one of whom is killed in the blast and the other is shot by Garry after his actions are misunderstood as hostility. The men, ignorant of the creature's identity, decide to adopt the dog and carry the dead Norwegian to the rec room, where Palmer offers to fly Dr. Copper to the Norwegian camp (which he refuses without hesitation). As helicopter pilot R.J. MacReady and the doctor leave for the camp, the dog is left to roam the outpost - finding an isolated victim in the living quarters.
Several hours later, as evening fell, Copper and MacReady return from their investigation with the charred remains of a split-faced creature - which is laid out in front of all the men. During the night, the men are awoke by the building's fire alarm, triggered by MacReady after hearing a disturbance in the dog kennels. Palmer emerges from the earlier victim's room and heads to the kennel with the others, witnessing the Dog-Thing's attempted assimilation of 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. Palmer, along with the other men, is drawn outside by the discovery of the half-assimilated Bennings, who is promptly doused with kerosene and ignited. After being conspicuously absent during Blair's break-down and incarceration in the tool shed, Palmer reappears following Copper's discovery that the blood locker had been opened by key, its contents destroyed and locked again - preventing a possible blood serum test and creating paranoia as Garry and Copper are accused of sabotaging the supplies.
After the remaining biologist, Fuchs, goes missing during a deliberate power outage, MacReady organises a search party and assigns Palmer with Windows. The agitated man vehemently disagrees with the decision, stating that he wants to go with Childs instead - causing the paranoid men to argue. The situation is resolved when MacReady leaves Childs, Norris and Palmer behind, taking Nauls and Windows with him to investigate outside. After approximately forty minutes has elapsed, the men begin to suspect that something has happened to the search party and they begin to barricade the doors. After Nauls makes his way back to the entrance, Palmer lets him in and asks where MacReady is. Nauls explains that he cut the pilot loose after discovering a scrap of torn clothing containing his name tag. Palmer and Norris begin to theorize on when Mac was likely assimilated, with the former using the opportunity to once again hurl an accusation at Windows. Somehow finding his way back to camp without a guide line, MacReady attempts to open the door, but finds it locked. Palmer suggests opening it to incinerate him, but Childs decides to lock him outside in the severe blizzard. In desperation, MacReady breaks into the storage room and threatens the rest of the crew with dynamite. In the course of the stand-off, Nauls and Norris unsuccessfully attack MacReady from behind, causing Norris to seemingly suffer a heart attack.
The men rush him to the medical lab, where Copper attempts to restart Norris' heart by defibrillation. The electrical shock, however, reveals the man to be an imposter and it attacks Copper, killing him by biting off his forearms. As a spindly creature explodes from the chest cavity MacReady torches it with a flamethrower, causing its head to tear away from its body and grow spider legs with pair of eyes on stalks. It hides under a nearby desk and then attempts to scuttle off, only to be incinerated when spotted by Palmer and Windows. In a bid to determine the identity of the remaining crew, MacReady improvises a rudimentary blood-test involving a heated copper wire and samples taken from the men. Noticing how every part of the Norris-Thing had an instinctive desire to survive, MacReady theorised that a creature's blood would attempt to flee from a hot needle. Dipping the heated wire into a Petri dish containing Palmer's blood, the organism unexpectedly reacts, jumping out of the dish with a shriek. Shocked, MacReady dropped the sample to the ground, where it promptly liquefies and flees. In the chaos, the Palmer-Thing, exposed, transforms and shreds off its bonds. It then fatally mauls Windows before being finished off by MacReady using a stick of dynamite.
Palmer was initially shown to be a very laid back individual and somewhat of a stereotypical stoner, always listening to music on a cassette with his headphones and smoking marijuana while watching quiz shows with Childs during lights out. He also appeared to have a good relationship with Nauls. He was somewhat of a conspiracy theorist and heavily believed the government was hiding alien life from the public eye, even referencing Chariots to the Gods?. As the film progressed, however, he slowly became more superstitious and even helped Childs turn on MacReady, prepared to burn him with a surprise attack. He retained his rather sarcastic sense of humour, even in the presence of the Norris-Thing's grizzly reveal and the Head Spider. He showed remorse for Chopper and Clark, believing their blood testing to be unnecessary due to them being dead. However, it is important to note Palmer was assimilated and replaced with an imitation at this point, which would explain his sudden brash behaviour, despite the fact his imitation was able to replicate the more calm and remorseful personality for a certain amount of time. He believed in alien life very unsuspiciously, believing the government to know all about them.
- 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. By alternative interpretation, it is believed that, due to the distinct shape of their collar, the individual was in fact Norris, and Palmer was assimilated by the Norris-Thing at a later point, with the shredded clothes belonging to him.
- Palmer is Childs' room-mate as seen earlier in the movie and appeared to have a good relationship with Nauls. He and Windows appeared to dislike each other, with Palmer's imitation ironically being responsible for Windows' death.
- As a nod to the original motion picture's plant-based version of the monster, Palmer and Childs hesitate in a deleted scene whether to keep their pots of marijuana or destroy them; as the Thing may have even infected those.
- It is possible that Palmer targeted the Norris-Thing's Spider Head to avoid suspicion of itself. However, careful observation of the scene demonstrates that Windows had already turned his head and noticed the spider-head Thing, in which case Palmer quickly exclaimed at it simply because the spider-head's cover was already blown.
- Another debatable theory that arises from whether or not Childs was an imitation at the end of the movie is the scene where Palmer hands Childs his cigarette while he is watching a quiz show on a monitor. As it was around the time MacReady and Copper returned to the base, Palmer had possibly been assimilated at this point, and possibly once he passed the cigarette to Childs, it may have been contaminated at the time, leading to further speculation that Childs may have been an imitation as well. However, as Childs most likely died from being exposed to the cold, this theory is (for some) debunked. For some reason, Palmer never thought to assimilate Childs while they were alone together, which was surprisingly often.
- There is a theory that he was actually the one who destroyed the blood bank because when everyone was arguing with each other about the sabotage of the blood bank, he never took his headphones off to hear the conversation.
- Palmer and Norris spent a lot of time close to each other later on in the film, hinting at their close connection of both being assimilated.