Stiles is a man wrongly convicted of murdering eleven people. He is offered a choice between execution and cooperating with an experiment. His religious beliefs don't allow him to choose execution, which would amount to suicide, so he is forced into participating in a genetic experiment to splice his genes with extraterrestrial DNA.
As a result Stiles changes into what appears to be a horrific monster with enhanced senses and mental capacity. His captors allow him to escape so that they may hunt him down. When the end comes near for Stiles, the tables turn as aliens resembling the now completely mutated Stiles appear. The aliens and Stiles beam away, leaving his pursuers to realize that they were being tested by the aliens and that they had failed the test.