It deals primarily with the social effects of drastic age rejuvenation technology and first contact theory.

A wealthy industrial billionaire, Cody McGavin, offers to put up billions of dollars to perform a "rollback" on not only Sarah but Don as well.

This process, which reverts a person's body to its condition when the subject was 25 years old, is successfully performed on Don, but fails to work with Sarah.

This leaves Sarah gradually creeping toward death while Don's life begins anew.

Much of the story focuses on Don as he discovers the advantages and disadvantages of being young again, with periodic flashbacks to when Sarah translated the first alien message.