Arthur (Russell Brand) is a rich, alcoholic playboy with no regards to his working life. After another drunken run-in with the law, his aloof mother has had enough and forces him to marry Susan (Jennifer Garner), a proper business woman, or else he will lose his inheritance. Just as he's engaged to Susan, he meets Naomi (Greta Gerwig), a free-spirited girl who Arthur thinks is perfect for him. Any attempts at holding down a job are fruitless, so Arthur has to decide, what is more important: love, or his mother's money.