A crew of astronauts on a multi-generational mission descend into paranoia and madness, not knowing what is real or not.

Set in the near future, the film chronicles the odyssey of 30 young men and women who are sent deep into space on a multi-generational mission in search of a new home. The mission descends into madness, as the crew reverts to its most primal state, not knowing if the real threat they face is what's outside the ship or who they're becoming inside it.—Lionsgate

With the future of the human race at stake, a group of young men and women bred for intelligence and obedience embark on an expedition to colonize a distant planet. When they uncover disturbing secrets about the mission, they defy their training and begin to explore their most primitive natures. As life on the ship descends into chaos, they soon become consumed by fear, lust and an insatiable hunger for power.—yusufpiskin

In 2063, astrophysicists on a climate-change-ravaged Earth find a habitable planet. A scouting mission is sent, although the 86-year flight means that the grandchildren of the launch crew astronauts will be the ones who reach the planet. To help the launch crew cope with the knowledge that their remaining lives will likely be spent mostly in flight, the original 30 are bred through IVF and kept in isolation from the rest of the world. In order to extend their time in flight, they are launched on the Humanitas spaceship as pre-teens, with a single adult, senior program commander Richard, to guide them through the early part of the journey. To conserve resources, the plan is for IVF to be performed when the crew turns 24, to be repeated on those offspring when they turn 24.

During the tenth year of the flight, Christopher and Zac discover that the grown teenagers are being given a blue chemical in their food to suppress sex drive and pleasure response, keeping them all docile and manageable. The pair stops taking the chemical, and their surging hormones drive them to become competitive, careless, and anxious to engage in sexual relations, specifically with their crew mate Sela, who has been trained to be the chief medical officer.

During a repair effort outside the Humanitas to address a failed Earth communication system, Richard, who has been serving as chief officer, is killed, apparently by an unseen entity, and a fire damages more ship systems. Christopher is voted the new chief officer, which upsets Zac, who then tells the others to stop ingesting the chemical. The mission descends into madness, as many of the young men and women revert to their most primal state.

Zac tells the others that an alien killed Richard, that he will protect them and let them eat all the (closely conserved) food they want, and convinces all but five to follow him rather than Christopher. Christopher and Sela, who have become a couple, find and repair a video disk that reveals that Zac killed Richard, precipitating the further systems damage, by turning on the electricity to the communications array while Richard was working on it. They show the others, but Zac still convinces many that an alien is inhabiting one of them, leading many to follow Zac in vigilante murders of anyone he targets.

Christopher inadvertently leads Zac to a hidden compartment on the ship, which proves to be weapons for their grandchildren to use on the planet. Christopher, Sela, and Phoebe are the only holdouts. Phoebe is killed, and the pack searches for Christopher and Sela. The pair tricks Zac into being ejected into space, and peace returns to Humanitas. Sela is then voted chief officer. The crew decides to permanently forgo the blue chemical and learn to manage their natural emotions, as well as falling in love and having children naturally, instead of via IVF as had been originally planned.

Decades later, Humanitas and its multi-generational crew arrive at the planet, which appears from orbit to be as earth-like as had been hoped. (copied from Wikipedia)