In the year 2050, NASA has discovered a distant planet that may hold life. The journey will take 85 years and three generations of a human crew to reach the planet. The first generation is cultivated in a lab from the sperm and eggs of brilliant scientists. Thirty children are raised and trained in isolation and then launched into space, accompanied by a single adult who has volunteered to go with them. All goes according to plan, except for a creeping fear among the young crew that there is something else on the ship, something they've never seen something alien.