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. When he examines its body, he doesn't notice its blood has dripped into his pipe. Lighting up and taking a few puffs, 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 throwback troglodyte with large hands, feet, dark skin, heavy body hair, and prominent brow ridges. He decides to take a few days off at Dr. Howard's remote cabin. Blake plans to learn whether he is the beast. Blake rigs the cabin with cameras on trip wires to record whatever happens 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. Madeline comes to and struggles with the beast. The forest ranger shoots the caveman when she breaks free, but he throws his axe, killing the ranger. The caveman collapses. Blake, once again himself, returns to the cabin and develops a photo, showing it to Madeline, who does not understand and asks why the beast is wearing Blake's clothes. 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