109 years ago, the Allied Mastercomputer- "AM" (voiced by Ellison himself!)- kills off all of humanity, with the exception of five individuals he keeps to torture within the Earth's center. Unlike the short story, these individuals do not interact with each other, and their backstories are significantly altered and expanded upon.
Ted (originally the narrator in the short story) is tortured with severe paranoia played on by AM.
Benny (the most altered from the short story) has been severely disfigured to appear like an ape, and must face the ghosts of those he has wronged in the past.
Ellen is forced to confront her extreme fear of the color yellow, with AM taunting her with the possibility of being able to destroy him.
Gorrister is a suicidal, apathetic man heavy with guilt from having his wife committed to a mental hospital. AM dangles the possibility of death in front of him, only to rip it away.
Nimdok, with no memory of his life, is forced to relive his past, where he is revolted to realize he was a Nazi scientist.
By going through the trials of these characters, you can finally confront AM in the hopes to stop his eternal torture of the last of humanity.