In 2009, Graeme Willy and Clive Gollings (Simon Pegg and Nick Frost) are two English comic book nerds and best friends who have travelled to America to attend the annual Comic-Con convention and to take a road trip in their RV to visit all the sites of major extraterrestrial importance. At night along the highway they investigate a crashed car and they meet and discover an alien named Paul (voiced by Seth Rogen) who is in desperate need of their help. Although shocked by the appearance of Paul, Graeme agrees to give Paul a ride, but Clive is not happy about the idea. Later, Lorenzo Zoil (Jason Bateman), a shady government agent, arrives at the site of the crashed car and informs his mysterious female superior over the radio that he's closing in on Paul, and she recommends using local law enforcement as back-up. Zoil then recruits two inept FBI agents, Haggard (Bill Hader) and O'Reilly (Joe Lo Truglio), to aid in his mission, without telling them the nature of their target.
