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.