Monster on the Campus (a.k.a. Monster in the Night and Stranger on the Campus) is a 1958 American black-and-white science fiction/horror film from Universal-International, produced by Joseph Gershenson, directed by Jack Arnold, from a script by David Duncan, that stars Arthur Franz, Joanna Cook Moore, Nancy Walters, Troy Donahue, and Whit Bissell. The film was theatrically released as a double feature with the British horror film Blood of the Vampire.

The film's storyline tells of a university science professor who accidentally comes into contact with the irradiated blood of a coelacanth, which causes him to "regress" to being a primitive caveman.

Monster on the Campus

Plot

Dr. Donald Blake, a science professor at Dunsford University, receives a coelacanth. A student, Jimmy, asks Blake if the fish is really a million years old. Blake replies, "It's the species that's old. No change in millions of years. See, the coelacanth is a living fossil, immune to the forces of evolution". Blake teaches his students that man is the only creature that can decide whether to evolve or devolve and that "unless we learn to control the instincts we've inherited from our ape-like ancestors, the race is doomed."

Monster on the Campus

Inside the lab, Blake scratches himself on the teeth of the partially-thawed coelacanth, accidentally sticking his bloody hand into the water-filled container which held the fish. Molly Riordan, the assistant to Dr. Cole Oliver, is with Blake and offers him a ride home. Blake says he does not feel well and passes out when they get to Molly's car.

Monster on the Campus

A person or persons unknown attacks Molly at Blake's home. Madeline Howard, Blake's fiancée and daughter of Dr. Gilbert Howard, president of the university, arrives and finds the home in shambles and Blake moaning on the ground. Madeline calls the police after seeing the corpse of Molly hanging by her hair in a tree.

Detective Lt. Mike Stevens and Detective Sgt. Eddie Daniels find a "deformed" handprint on a window and Blake's tie clasp in Molly's dead hand. They take Blake downtown when he admits that he cannot remember anything after getting into Molly's car.

Concluding that someone holding a grudge is trying to implicate Blake in Molly's murder, Stevens releases him. He assigns Daniels as Blake's bodyguard and tells Blake that Molly's autopsy showed she died of fright.

In his lab, Blake shoos away a dragonfly that lands on the coelacanth. The dragonfly later returns, now two feet in length. Blake and Jimmy try to catch the giant insect with a net when it lands on the coelacanth again. Blake stabs the dragonfly. While examining its body, he does not notice its blood has dripped into his pipe. Lighting up and smoking, he immediately feels ill. As the dragonfly shrinks back to its standard size, a large, hairy hand reaches out and squashes the insect. Then Blake's lab is trashed, and Jimmy's visiting girlfriend is killed. The police find huge footprints near her body and conclude they are from the same source.

Blake learns that the coelacanth has blood plasma preserved by gamma rays. If it gets into the bloodstream of an animal or person, it causes them to revert to a more primitive state temporarily. He realizes that he might have received a dose of the irradiated plasma. If so, then Blake has been reverting to a troglodyte with large hands, feet, dark skin, heavy body hair, and prominent brow ridges.

He decides to take some days off at Dr. Howard's remote cabin. Blake plans to learn whether he is the beast. He rigs the cabin with cameras on trip wires and injects himself with coelacanth plasma. His caveman self wrecks the room, trips the camera's wires, and is photographed. He grabs an axe and leaves.

While driving to the cabin, Madeline runs off the road and crashes when the caveman appears in her headlights. A local forest ranger arrives and calls the Dunsford police for help. The caveman carries the unconscious Madeline into the forest, with the ranger in pursuit.

Waking up, Madeline struggles with the beast. The ranger shoots the caveman when she breaks free. The caveman then kills the ranger with his axe and collapses. Blake, once again himself, returns to the cabin and develops a photo, showing it to Madeline.

Lt. Stevens, Detective Sgt. Powell and Dr. Howard arrive at the cabin. Blake tells them that he not only knows who the murderer is, but where to find him. Out in the woods, he explains to Howard what his experiment proved and injects himself with coelacanth plasma. Again transformed into the caveman, he chases Howard, forcing the two detectives to shoot him. As the beast lies dying, he slowly transforms back into Blake.