Former London constable Nicholas Angel finds it difficult to adapt to his new assignment in the sleepy British village of Sandford. Not only does he miss the excitement of the big city, but he also has a well-meaning oaf for a partner. However, when a series of grisly accidents rocks Sandford, Angel smells something rotten in the idyllic village.

As bass guitarist for a garage-rock band, Scott Pilgrim has never had trouble getting a girlfriend; usually, the problem is getting rid of them. But when Ramona Flowers skates into his heart, he finds she has the most troublesome baggage of all: an army of ex-boyfriends who will stop at nothing to eliminate him from her list of suitors.

Five friends who reunite in an attempt to top their epic pub crawl from 20 years earlier unwittingly become humankind's only hope for survival.