Ray (Chris O'Dowd) has been fired from his job as a costumed guide in a theme park attraction called "Star Ride". Ray's good friends Pete (Dean Lennox Kelly) and Toby (Marc Wootton) work at the theme park restaurant and they all decide to go to a cinema and pub after they leave.
Ray meets an American girl named Cassie (Anna Faris) who claims to have a time machine built into her body and whose job is to find and repair "time leaks" and stop "editors". Understandably, Ray's friends have some trouble believing him.
However, they end up traveling back and forth through time within the pub. Hints about their journey appear in different time stops. They meet a second time traveler, named Millie (Meredith MacNeill). Cassie is told about Millie and is immediately suspicious, with good reason. Cassie's time machine is taken offline and she finally meets Millie. Millie makes Toby an offer to die and be a legend which, of course, he refuses.
At the end of the movie, the three friends walk home wondering about the events in the pub when Cassie appears through a big glowing portal. She reveals that they have only fourteen hours to save the Earth (a reference to the film Flash Gordon), and urges them to go with her to a parallel universe.
Who appears through a big glowing portal?
Cassie