Shy, unassertive researcher Dr. Arthur Zeller daydreams about what it would be like if he could unlock the animal within him. It turns out his real life is that of a "doormat" for his co-workers and even for a bum who shakes him up regularly for "lunch money". All his brilliance and scientific accomplishments take a backseat to his personality and no one takes him seriously. He begins to try to make his dreams a reality by developing a kind of gene therapy which involves injecting himself with the genes for dominance extracted from primitive primates. This starts changing his entire personality. Zeller suffers from occasional lapses in which he reverts to the mind of a caveman and attacks his boss, and kills and eats a dog. The changes may improve his life on many levels but they are doing nothing for his love life. His affection towards his co-worker Dr. Laura White remains unrequited and so he decides to tip the scales. During a routine flu shot session, he surreptitiously injects Laura with the genes for submissiveness. The injection has severe side effects for Laura because her basic personality is not submissive at all, so she starts to pass out. Arthur takes her to his place and attempts to attack her, but regains control of his senses and begs her for help. He tells her what he has been up to and the shocked Laura decides to help him develop a way of reversing the process. Together they come up with an experimental antidote, but things go really bad when he reveals to Laura that he had injected her with the submissiveness genes. Seeing he blew his chance with her forever, he escapes into the night with a batch of his syringes. Laura has a change of heart and follows him to offer her help, but it's too late for Arthur who had already injected himself with a mega-dose of the ape genes.
At one point a character can be seen reading a newspaper. The headline is "Horowitz Executed", a reference to the event that does / does not happen in the parallel worlds created by time travel in the episode "Stitch in Time". This places the events of Descent in one of those universes meaning that those characters and the characters in this episode share a world.
Leland Orser ... Dr. Arthur Zeller Jenny Cooper ... Laura White (as Jenny Levine) Greg Thirloway ... James Feind John Novak ... Dr. Stansfield Frank C. Turner ... Mikulak Benita Ha ... Cute Lab Technician John 'Bear' Curtis ... Bum Robyn Driscoll ... Detective David Neale ... Security Guard