Robert Stoney, finds himself in a cage amidst World War II. He is in physical pain from the poor conditions and is often ill. One of his captors, a man by the name of Quint, talks with him and agrees to lighten his conditions some.

Stoney had first met Quint through a man he was seeing—Arthur. Arthur ended up working for the police and accused Stoney of a crime he didn't commit, as well as his homosexuality, thus landing him in prison.

However, amidst his illness, he awakes one night to a woman, Helen, in what used to be his cell. It turns out that the woman had made the cell disappear and that she is a robot from the future. Helen helps Robert escape and return to his studies. During this time, Robert begs Helen to tell him his life story in other timelines--ones where he was sexually tested on and eventually committed suicide. As Stoney works on his discoveries in physics, another character is introduced by the name of Jack Hamilton. This character strongly represents the author C.S. Lewis, and becomes interested in the work that Stoney is doing. Jack analyzes and argues with Stoney about his studies, but they eventually continue their debates at a bar where Quint intrudes. The two men grapple with Quint and eventually knock him unconscious and throw him into a pond.

Amidst intellectual turmoil, Jack eventually challenges Stoney to a formal debate in which they argue about whether or not machines can think. Armed with the promised assistance of Helen, Robert Stoney effectively explains his point with the use of logic and physics. Towards the end of the publicized debate, Jack confesses that his wife has cancer and Robert offers a genetic treatment as a cure, which Jack fervently declines. They end on a negative note.

As Helen departs Stoney, she upholds her promise and appears to Jack as an apparition, convincing him to show compassion to Stoney.