The passengers of a starship on a century-long voyage to populate a new world begin to question the true nature of their covert mission when 50 years into their journey, which began in 1963, a young woman turns up dead of suspicious circumstances.

Aaron investigates an explosion on Ascension, while Captain Denninger covers up its true cause. Elsewhere, Viondra suspects there is a traitor within her ranks of stewardesses after Councilman Rose becomes privy to inside information; something mysterious seems to be happening to young Christa Valis; and James Toback attempts to impress Nora by making a deal to get into Officers Training School.