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 and Rockliffe Fellowes. It is directed by Norman Z. McLeod with screenplay by S. J. Perelman and Will B. Johnstone.

Plot

On board an ocean liner bound for America, four stowaways hide in wooden barrels in the ship's cargo hold. After singing "Sweet Adeline", they are discovered and the ship's officers spend the rest of the voyage chasing and attempting to catch the stowaways who are running amok. Chico and Harpo pose as barbers and shave off an officer's mustache while he is sleeping; Groucho and Chico lock the ship's captain in a closet and eat his lunch; Groucho hides in the closet of the stateroom of gangster Alky Briggs and his wife, Lucille; Briggs leaves and Groucho begins romancing Lucille until he is caught and threatened by Briggs. Briggs is so taken by Groucho's nerve, he hires both Groucho and Zeppo to cover him while he confronts Big Joe Helton, a rival mob boss and gives them loaded guns, which they immediately ditch in a bucket of water. Chico and Harpo disrupt a chess game and confiscate the board, taking it into the stateroom of Helton and his daughter Mary. After they scare off Briggs during the confrontation with Helton, the mobster is impressed and hires Chico and Harpo to be his bodyguards. Groucho later offers his own protection services to Helton, who says he will think it over.