Neil Clarke (Simon Pegg) is a perfectly average human, trying to win the affection of his beautiful neighbor Catherine (Kate Beckinsale). As a test to determine if the planet Earth is worth saving, powerful aliens in space (voiced by the Monty Python team) have granted him the ability to do anything he wants. As Neil struggles to deal with his newfound powers, he must rely on his loyal canine companion (voiced by Robin Williams) to help him along the way.