In the distant future, a genetic research station is located on the remote desert planet of Xarbia, and 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 has killed all of the laboratory subject animals before cocooning itself within an examination booth. After Subject 20 hatches from its cocoon, it begins killing the personnel at the station, starting with the lab tech charged with cleansing the subject lab of the dead animal test subjects. Professional troubleshooter Mike Colby (Jesse Vint), accompanied by his robot pilot and assistant SAM-104 (Don Olivera), are 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, Dr. Gordon Hauser (Linden Chiles), his assistant Barbara Glaser (June Chadwick), lab assistant Tracy Baxter (Dawn Dunlap), the station head of security Earl Richards (Scott Paulin), mechanic and tech expert Brian Beale (Raymond Oliver), maintenance worker Jimmy Swift (Michael Bowen) and Dr. Cal Timbergen (Fox Harris), the chief of bacteriology. As Subject 20 continues to unleash a storm of gory fatalities that decimates most of the station crew (first starting with Jimmy, and later Earl), the lid on the deception is finally withdrawn: Subject 20's genetic design incorporates human DNA. Furthermore, Cal discovers that its method of killing is most horrifying: this beast injects its prey with the Proto B DNA strain which then proceeds to remove all genetic differences within specific cells. The result is a terrifying death as the victim's living body slowly erodes into gelatinous pile of pure protein which subject 20 then uses for food. After Tracy and Colby have an encounter with the growing and mutating Subject 20 mutant, Colby, Hauser, Beale and SAM-104 venture out into the planet's desert landscape to find the mutant, which leads them back to the facility after the mutant kills Hauser and damages SAM-104.
Tracy and Barbara confront the mutant in the control center to try to communicate with it, only for the creature to kill Barbara as well. Beale is next to go when he attempts to fix the communication equipment when the mutant electricutes him on a circut pannel, before it injurs Cal. After its final mutation, the creature evolves into a huge insect-like being with a large mouth full of sharp teeth which chases and terrorizes Tracy as she runs through the facility. Colby, SAM-104 and the injured Cal take refuge in the lab where Cal (who had been coughing throughout the movie) reveals that he has terminal lung cancer and that it can kill the mutant. Cal makes Colby cut into his chest to remove a large baseball-sized tumor along his right lung and above the liver, but Cal dies during the crude surgery. Tracy then runs in being chased by the creature, which then destroys SAM-104 after it shoots a laser gun at it, and then stabs it in one of its eyes with a scalpel. Colby manages to get close enough to feed the mutant Cal's tumor and as a result, the creature's body genetically self-destructs from within as it collapses to the floor, leaving Mike Colby and Tracy as the only survivors..