Plot

A scientist discovers a formula enabling him to pass through solid surfaces, but he also rapidly ages, which forces him to kill humans in order to reverse the aging process by absorbing his victims' energies.

Two brothers, scientists Scott and Tony Nelson, develop an amplifier that enables a person to enter a 4-dimensional state, which allows him to pass through any object. Scott experiments on himself and discovers that each time he passes through something he ages rapidly. He begins killing people, sucking out their life energies and regaining his youth as a result. It falls to Tony and Scott's girlfriend Linda to try to put a stop to his murderous rampage.—Doug Sederberg <vornoff@sonic.net>

Electrodynamics scientist Tony Nelson (James Congdon) experiments with the fourth dimension, a dimension defined as the intermingling of atoms so they take up the same space at the same time, by attempting to push a wooden pencil into a steel block with the aid of a radiated force field. His experiments, although briefly successful, result in a fire that destroys his laboratory.

After his boss fires him, Tony is forced to visit the Fairview Research Center, where his brother Scott (Robert Lansing) leads a team of physicists struggling to perfect cargonite, an impenetrable metal. Although the brothers have quarreled in the past, the staid Scott welcomes Tony and introduces him to the woman he plans to marry, his assistant, Linda Davis (Lee Meriwether). Tony is entranced by Linda but, trying to deny his attraction to her, refuses her suggestion that he stay in Fairview and work alongside Scott. Over the next few days, however, Scott, absorbed in his work, leaves the two alone frequently, and one day they find themselves in an embrace, although Tony soon tears himself away.

The next day, Scott's group exposes cargonite to radiation in order to prove that it cannot be destroyed, but the experiments fail. In his frustration, Scott continually checks the metal, exposing himself to radiation. Tony interrupts to announce that he is leaving town immediately, and although he tries to explain his real reasons, Scott assumes that Tony is not dedicated enough to his work. Just then, Linda announces that the experiments have finally succeeded.

At a press conference the next day, Theodore J. Carson, Fairview's owner, takes credit for the invention, which, as it is impervious to heat, bullets and bombs, will reap a fortune in building and government revenues. At home, however, Tony declares to Scott and Linda that his experiments prove that any metal can be penetrated, and describes how he pushed the pencil through steel by concentrating on it intensely. Because Tony has not been able to repeat his accomplishment, Scott scoffs at its scientific value, causing Tony to storm off in anger. Linda follows him outside and there declares her love for him, and although Tony returns her feelings, he explains that years earlier he ran off with Scott's fiancée, causing a rift between the brothers that he dares not repeat. At Linda's urging, however, they kiss. Soon after, Tony accepts a job at Fairview, where he continues his 4D experiments clandestinely.

One day, Scott visits Dr. Brian Schwartz, who informs him that radiation exposure has caused his brain impulses to become stronger than is normal. When Scott overhears Linda and Tony discuss their affair, Tony tries to talk to him about it, but Scott refuses to listen. Instead, that night he asks Linda to marry him, leaving angrily after she suggests that their relationship is merely habit. He returns to the lab, breaks into Tony's locker and, ignoring the searing pain in his head, begins experimenting with Tony's force field, not realizing that his conniving assistant, Roy Parker, has stolen Tony's notes off his desk. Soon, Scott calls Tony to inform him that he has succeeded in passing his hand through a cement block. Tony rushes to the lab to check his findings, and there discovers that his force field has been inert, indicating that Scott has achieved his 4D experiment through brainpower alone. Scott then forces Tony to promise not to tell anyone of their discovery so Carson cannot steal it, and ignores his brother's pleas for him to visit the doctor once again.

During his walk home, Scott, intoxicated with his new power, robs a series of stores and banks by passing his hand through glass windows and steel safes. Realizing he is losing his mind, Scott staggers to Brian's house and begs him to help, but when he touches Brian, the doctor immediately ages dozens of years and dies. Scott realizes that, although the extreme exertion of using his powers ages and weakens him, by killing others he can absorb their energy and replenish his strength.

Meanwhile, Parker brings Tony's notes to Carson and, claiming them as his own, demands his own research team. Carson, however, doubts that the ideas are Parker's, and the next morning calls in Scott, who denies any knowledge of the 4D notes. To protect his powers, Scott then hides the force field in the radiation machine, and later visits Carson and kills him sadistically. Police captain Rogers investigates the deaths, and when he informs Tony that he has found a thousand-dollar bill embedded in a safe wall, Tony realizes Scott is the culprit. That night, Scott wakes Linda and demands she accompany him, but leaves after she faints in terror. At the same time, Tony searches Scott's apartment and finds the stolen money, which he brings to Rogers. Together, they plan to trap Scott while he is not four-dimensional, a state that renders him impervious to ammunition, but before they can find him, he kills several more strangers.

When the police finally find and surround Scott, he walks through building walls to elude them. Hours later, Scott returns to the lab, where Tony and Linda are waiting, to retrieve the force field device. When Tony discovers his presence, he turns up the power in the radiation machine in an attempt to kill Scott, but Scott spots Tony and chases him out of the area. Scott then turns his attentions to Linda, and in order to kiss her, reverts to a non-4D state. Linda submits to Scott's kiss but then pulls out a gun and shoots him. Wounded and weakened, Scott nonetheless raves that he is indestructible and climbs through a wall. Tony and Linda watch as Scott slowly pulls his hand through to the other side, his strength, and perhaps his life, exhausted.

The film ends with the onscreen words, "The End?" suggesting that "Scott Nelson" might still be alive.