Arthur (Russell Brand Russell Brand), the heir to the rich Buck family, is a well-known Peter Pan-style figure in New York City, and his mother, who runs the family company, is under pressure because he has repeatedly reported absurd behaviors such as a Batman rampage. Arthur's behavior like an ignorant child repeatedly requires the old housekeeper Hobson (Helen Mirren Helen Mirren) to clean up the mess. Her mother can't stand Arthur's behavior of tarnishing the company's reputation and threatening Arthur to marry her capable female assistant Susan. Susan has career ambitions and is determined to rely on this marriage to improve her family status as a builder. Arthur, who saw Qian bowing to his mother, ran into an unlicensed tour guide Naomi (Greta Gregg Greta Gerwig) in the street, whose elegant demeanor made Arthur sprout his love. at the fork between marriage and love, Arthur hopes to find a happy ending, which may be the strongest challenge he has ever faced.