Jess (Melissa George) is a waitress and single mother to Tommy (Joshua McIvor), who has autism. One morning, the doorbell rings while she goes about chores, but no one is there when she answers. She then packs up for a trip with her friend Greg (Michael Dorman) on his boat. Joining them are Victor (Liam Hemsworth), a runaway teenager who lives with Greg; Sally (Rachael Carpani) and Downey (Henry Nixon), long-time friends of Greg who are married; and Heather (Emma Lung), a friend of Sally's. Jess looks exhausted when she greets them and naps for the first few hours of the trip. Tommy was also invited to come along, but Victor tells Greg that Jess zoned out when asked where he was before claiming he was at school. Some time later, the wind suddenly dies down entirely and an electrical storm approaches the boat. While radioing the coast guard, Greg picks up a distress call over the communication link, but requests for coordinates go unanswered. The storm soon reaches the boat and capsizes it, during which Heather is swept out into the water. When the weather clears, the others climb onto the upturned boat, stranded and unsure of what to do.
A cruise ship soon approaches them and they shout for help, quickly boarding it as it passes, only to find no one on the deck or in the hallways. Jess feels an increasing amount of déjà vu as they wander the halls. While they examine a display case for Aeolus, the ship's namesake, they hear a noise and find a set of keys, which Jess recognizes as hers. The group soon finds a dining hall, where Jess spots someone watching them and Victor runs off after them. Jess and Greg continue looking and find a room with a bloody message written on a mirror directing them to the theater. Jess leaves Greg after a disagreement and returns to the dining hall where she is found by Victor, who is bleeding from a head injury. He tries to strangle her, and dies from his injury as she escapes. She follows the sound of gunfire to the theater, finding Sally and Downey kneeling over Greg's corpse. They accuse her of killing Greg and demand to know why she directed them to the theater, both of which Jess denies. The actual killer guns down Sally and Downey from above. Jess flees and soon reaches the front deck, where she disarms the killer after a brief struggle. The killer speaks incoherently under the mask before falling over the side of the ship.
After finding an active phonograph in the cabin, Jess hears yelling from off the ship and looks over the side to find herself and the others yelling for help from the upturned boat. Jess follows them after they board, but she drops her set of keys in the hallway near the display case and is nearly spotted by her counterpart in the dining hall. She runs outside and is found by Victor, but she accidentally injures his head while trying to explain things. She flees and finds a locker room with clothing and shotguns the killer used earlier, as well as notes on the floor that say to kill everyone who boards, which she realizes were written by her. She takes a shotgun and confronts herself and Victor in the dining hall, though her counterpart flees when she cannot kill her. She then runs to the theater and shoots at the killer, saving Sally and Downey. She leaves them to get Victor, intent on escaping the ship, only to find he was thrown overboard. The killer, revealed to be another Jess, finds and leads Sally and Downey to the room with the bloody message. She then attacks and savagely kills Downey, stabbing Sally in the process.
Sally flees and is chased by the current Jess. She reaches a communication room and begs for help over the link, revealing her to be the distress caller picked up on Greg's boat. Jess eventually catches up to her on an upper deck, the floor of which is covered with Sally-corpses, and watches from above as the newest Jess kills the killer Jess and throws the body overboard. Sally soon succumbs to her wound, at which point the upturned boat and everyone on it returns again, revealing that the time loop repeats itself after everyone is killed. Now desperate to get home, Jess disposes of the bodies, leaves the message on the mirror with Downey's blood and directs Sally and Downey to the theater. She then dons the killer's outfit and kills everyone in the theater except her counterpart, who she chases to the front deck. She is disarmed during the struggle, and tells her counterpart to kill everyone when they board before falling over the side.
She awakens on a beach and hitchhikes home, only to find herself returned to the morning of the trip. As she watches from outside, it is revealed that Jess is abusive toward Tommy, whose autism bothers her. Jess rings the doorbell and runs to get a hammer, then enters the house and beats her other self to death with it. This is seen by Tommy, and Jess hugs him and assures him he had a bad dream, echoing the film's first scene. She puts the body in a duffle bag and loads it into the car, then leaves with Tommy, promising she won't abuse him anymore. A seagull suddenly hits the windshield, leaving bloody tracks, and she pulls over to toss it over the edge of the embankment, but finds multiple dead seagulls below. Realizing she's still trapped in the loop, Jess tosses it and gets back onto her car and drives on, but Tommy panics over the blood; as she tries to calm him down, she veers into the other lane and is hit by a truck. In the aftermath, as she watches people gather around her dead body and Tommy's, a taxi driver approaches and comments that nothing can save Tommy before offering her a ride. She asks to be taken to the harbor, where she joins the others on the boat, intent on preventing her son's death, and hopefully finally escaping the loop.
- Melissa George as Jess
- Joshua McIvor as Tommy
- Jack Taylor as Jack
- Michael Dorman as Greg
- Henry Nixon as Downey
- Rachael Carpani as Sally
- Emma Lung as Heather
- Liam Hemsworth as Victor
- Bryan Probets as Driver
Connections to Alice in Wonderland
- The Jess character represents Alice; Jess/Alice both enter a surreal-like world.
- The Aeolus represents Wonderland.
- In one scene, Jess stares into a mirror and then when she hears sound coming from outside, the camera, along with Jess, seems to move "through the looking glass".
- The driver, who takes Jess to the harbor represents the White Rabbit, leading Alice to Wonderland.
- Fear Comes in Waves
- Save Our Souls
- The Forecast is Evil
- A Passage to Hell