Aaron Green (Jonah Hill) is an ambitious 24-year-old who has been given a career-making assignment. His mission: Fly to London and escort a rock god to L.A.'s world famous Greek Theatre for the first-stop on a huge comeback tour. British rocker Aldous Snow (Russell Brand) is a brilliant musician, but due to a bad break up and nose-diving career, has fallen off the wagon and is now a drunken disaster. As the countdown to the concert begins, one innocent young man must navigate a minefield of London drug smuggles, New York City brawls and Vegas lap dances to deliver his charge safe and, sort of, sound. He may have to coax, lie to, enable and party with Aldous, but Aaron will get him to the Greek.