Earth is over-populated and dying, so they send a large ship to colonize another planet where robot probes have discovered life. Ben Foster plays the lead character Corporal Bower. He is on a ship bound for a distant planet that contains the last remaining humans and all the earth plants and animals. Its mission is to colonize a new planet so that human beings will continue, since earth will be destroyed. Bower wakes up from suspended animation in a life support chamber. He is disoriented. He cannot remember his mission, who he is, where he is, or how he got there. He immediately notices something is wrong with the ship, when it goes into a power overload that rocks the entire structure. He also notices that he is tattooed with crew number 5 on his forearm with his name. Slowly his memory starts to come back. He looks for other crewmembers because they are supposed to relieve him, but he cannot find anyone. The ship's systems are dead, so he is unable to use anything. He is trapped in the transport bay because there is no way to open the massive door. There is one life support chamber with Cooper's name on it, which is empty. Another one labeled Payton, has a man inside. The power surge comes again, causing Payton (played by Dennis Quad) to be released. After Payton recovers from the effects of the long sleep, they decide the best thing to do is for Bower to try the vents to find a way to escape the transport bay then come back to open the door from the outside. Payton is a Lieutenant so he is the ranking officer over Bower.
Bower crawls through the vents and finds Cooper, the missing member of his crew, dead, near an opening. Bower gets out of the vents but his communication with Payton is cut off. While searching, he finds another person, Nadia (played by Antje Traue) who runs away when he discovers her. He gives chase. Bower finds another crewmember hanging dead in the hallway from a wire. Nadia attacks him from behind, puts a knife at his throat, and then demands his shoes. Before he can give up his shoes, they are both attacked by semi-human monster-like creatures that are very fast and very strong. These creatures are called "The Hunters" and they see humans as prey.
Bower finds another crewmember hung up on a wire. This one is alive. He cuts him loose. His name is Shepard (played by Norman Reedus). Bower tells him he wants to get to flight deck to speak with the commanding officer. Shepard tells him there is no one in command. The Hunters attack them. Shepard is killed but Bower escapes. Bower regains radio contact with Payton and tells him the ship is full of monster-like humanoid creatures. Bower runs into another crewmember Mahn (played by Cung Le) who speaks only Chinese. Through sign language Bower convinces Mahn to show him how to get to the reactor, so he can reset it, to get power back to all the ship's systems to give them a chance to secure themselves from the Hunters. Nadia reappears and at first they start to fight again, by Bower convinces the two of them to work together with him. Nadia shows them the area she has been protecting which contains samples of all of earth's biology to be used for the colonization of the planet Tanis which is their destination.
The path to get to the reactor core is extremely dangerous. They must cross over the most popular hunting grounds of the Hunters where many life support pods have already opened. The Hunters see this area as an easy meal. They encounter the Hunters and fight with one of them. It takes all three just to kill one Hunter and they are brutally beaten in the process. Then many more Hunters arrive. The three run away. A life support pod opens with a man inside. The Hunters stop to eat him, giving the three a chance to escape.
While trying to escape, they run into Leland (played by Eddie Rouse) who has survived a long time by hiding. At first, he is friendly and he tells them the history of the ship as he recalls it from drawings scratched into the metal walls. The ship left earth as the last hope of humankind. Most of the ship operated automatically so there was only a three-person crew required to fly the ship. They went crazy with a disease called "pandorum" which is a kind of insanity caused by being in space for a long time or extended periods of suspended animation. Two of the three command crew were killed by the single one who went mad. He let some of the other humans out of the life support chambers to abuse them and torture them. Some of the humans had been genetically modified so that they would rapidly evolve on the new planet Tanis, but these modifications caused them to mutate into the monster-like creatures that now inhabit the ship. Bower thinks since he is part of crew 5 and every crew was supposed to serve for 2 years before they awaken the next one, that they have been gone from earth only 8 years but the truth is they have been asleep for almost a thousand years while the monster-like creatures had free run of the ship.
After explaining the history, Leland drugs them, ties them up, and hangs them up to save them for eating later. Even he is still human he has become a cannibal to survive. The ship shakes again violently from the troubles in the reactor core. Bower convinces Leland to let them down, because otherwise the ship will be destroyed within the hour if he cannot reset the reactor to get the ship's systems powered. Leland realizes it is the truth. Leland leads them to the reactor core. Bower has to crawl through a massive pile of sleeping Hunters to get to the reactor core. He disguises himself and crawls amongst them. They wake up to realize there is a human amongst them, but he has just enough time to get to the reactor to reset it before it is too late. After that, the Hunters chase them as the run back to the flight deck, now that the ship is operational. Mahn is killed. Leland is caught and killed. Bower and Nadia make it back.
Meanwhile, Payton has been hallucinating from the space illness. Payton is actually the third member of the 4th command crew, the one that killed all the others. He fights with an imagined evil version of himself, making his way to the flight deck as well. When Bower and Nadia arrive, Payton has completely lost it. They fight until Bower insists they open the view portal so they can see where they are. At first, they see only blackness, no stars at all. Then they suddenly see ocean creatures swimming above them. The ship has automatically landed itself on Tanis. Bower fights with Payton who has gone completely insane. Bower fires his weapon, which causes the view portal to crack open and water to rush in. Bower forces Nadia into a life support pod and launches it to the surface. Payton and all the monster-like creatures are left behind to drown in the ship. About 1,200 other pods, that contain humans, are automatically launched to the surface by the ship's response to the emergency. This is all that is left of the human race, yet enough to start the new colony.
Best part of story, including ending:
It's a great sci fi action film with lots of exciting moments. I like it that the monsters are mutated humans not alien life forms.
Best scene in story:
When they discover they are not in space but have landed and are underwater. It is a startling revelation.
Opinion about the main character:
Bower gets the female in the end, which is heroic, especially since this woman was trying to kill him when the first encountered each other.