Married couple Jack and Terry Linden are experiencing a difficult period in their relationship. When Jack decides to step outside the marriage, he becomes involved with Edith, who happens to be the wife of his best friend and colleague, Hank Evans. Learning of their partners' infidelity, Terry and Hank engage in their own extramarital affair together. Now, both marriages and friendships are on the brink of collapse.

Twelve extremely talented men and women have been chosen to be part of the Phaeton mission, a 10-year trek to explore a distant planetary system. In order to endure the stress of being confined to their high-tech vessel, the crew passes the time using advanced virtual reality modules that allow them to take on various identities. But as the ship approaches a critical phase of their journey, a deadly flaw is discovered in the virtual system, forcing them to question if someone onboard might be a killer.