"A Boy and His Dog" is narrated by Vic, a teenaged boy who has a telepathic dog named Blood. The story is set in 2024 post-apocalypse America. Rubble, craters, and molten metal mark the landscape. There are two civilizations of survivors - those above ground and those below. Those who live below are called "downunders," and their cities resemble those of pre-World War I America. Vic lives in the wreckage above ground and is a "solo," which is someone who is not a member of one of the gangs (called "roverpaks") that wander the streets.

As the story opens, Vic tells Blood to find him a woman, but Blood is unsuccessful because most women are downunders. Blood, like most dogs who stay with solos, was bred for intellect, telepathy, and an acute sense of smell. He relies on Vic for food because he lacks the ability to...