Monkey Business is a 1931 American pre-Code comedy film. It is the third of the Marx Brothers' released movies (Groucho, Harpo, Chico and Zeppo), and the first with an original screenplay rather than an adaptation of one of their Broadway shows. The film also features Thelma Todd, Harry Woods and Ruth Hall. It is directed by Norman Z. McLeod with screenplay by S. J. Perelman and Will B. Johnstone. Much of the story takes place on an ocean liner crossing the Atlantic Ocean. Plot On board an ocean liner, four stowaways hide in barrels in the ship's cargo hold. After singing "Sweet Adeline", they are discovered. The naval officers spend the rest of the voyage chasing and attempting to arrest the stowaways. Chico and Harpo disrupt a chess game and confiscate the board, taking it into the stateroom of racketeer Big Joe Helton and his daughter Mary, during a confrontation with rival gangster Alky Briggs. After they scare off Briggs, Big Joe hires Chico and Harpo to be his bodyguards. Groucho dances and romances with Briggs' wife, Lucille, until he is caught and threatened by Briggs. Groucho's audacity convinces Briggs to hire him and Zeppo. Briggs gives them loaded guns, which they immediately ditch in a bucket of water. Groucho offers his services to Big Joe, who says he will think it over. As the ocean liner is about to dock in the United States, the stowaways realize that to get off the boat, they must steal passports and fool customs officials. Zeppo steals the passport of movie star Maurice Chevalier, and demonstrates his ability to mimic Chevalier's singing. The four butt in line at customs and Zeppo impersonates Chevalier. He is unsuccessful, however, and passes the passport to Chico, Groucho and Harpo, who each attempt unconvincing portrayals of Chevalier singing the same song, with Harpo resorting to a phonograph strapped on his back with an actual record of Chevalier singing. The four escape the authorities after hiding under a covered load of baggage. Big Joe and his daughter, whom Zeppo met and romanced on board, host a party at which Groucho makes announcements, Chico plays piano and Harpo plays harp. Briggs' men kidnap Big Joe's daughter and take her to an old barn. The former stowaways follow and a fight ensues. The daughter is rescued, and Groucho attempts to find a needle in a haystack. Except in the credits