FORBIDDEN WORLD

In the distant future, at a genetic research station located on the remote desert planet of Xarbia, a research team has created an experimental lifeform they have designated "Subject 20". This lifeform was built out of the synthetic DNA strain, "Proto B", and was intended to stave off a galaxy-wide food crisis. However, Subject 20 mutates rapidly and uncontrollably and kills all of the laboratory subject animals before cocooning itself within an examination booth.

Military officer Mike Colby, accompanied by his robot assistant SAM-104, is called in to investigate the problem. After Colby settles in, his decision to terminate Subject 20 to prevent further deaths is met with research-minded secrecy and resistance. The staff of the station includes the head of research, Gordon Hauser, his assistant Barbara Glaser, lab assistant Tracy Baxter, lab technician Jimmy Swift, electrician Brian Beale, the station's head of security, Earl Richards and Cal Timbergen, the medical doctor.

When Subject 20 hatches from its cocoon, it begins killing the personnel at the station, starting with Jimmy, who was charged with cleansing the subject lab of the dead animal test subjects. As Subject 20 continues to kill most of the station crew, the reason for the deception is revealed. Subject 20's genetic design incorporates human DNA, and its method of killing is to inject its prey with the Proto B DNA strain which then proceeds to remove all genetic differences within specific cells. The result is that the victim's living body slowly erodes into a gelatinous pile of pure protein which Subject 20 consumes for sustenance. After its final mutation, where the creature evolves into a huge insect-like being with a large mouth full of sharp teeth, the creature is slain when it eats Cal's cancer-ridden liver, its body genetically self-destructing from within. Mike and Tracy are left as the only survivors from Subject 20's rampage.

Subject 20 is ultimately destroyed when it consumes a cancerous liver, causing its genetically unstable body to self-destruct. Only Mike Colby and Tracy Baxter survive the mutant’s rampage.

The film concludes with the experimental organism undone by an unexpected biological flaw—eating cancerous tissue—which triggers its self-destruction. This ending underscores both the unpredictable dangers of unchecked genetic engineering and the idea that scientific hubris can be its own undoing. The survival of Colby and Tracy suggests that brute resourcefulness, rather than scientific ambition, is what endures in the face of catastrophe.