Monkey Business

Four stowaways conceal themselves in wooden barrels aboard the ocean liner bound for America. They hide in the ship's cargo hold, managing to stay undetected as the voyage unfolds. Their disguise will be undone when they begin singing, drawing attention to themselves.

The stowaways are discovered after singing "Sweet Adeline". The ship's officers begin a chase that lasts the rest of the voyage. The group runs amok, causing chaos as they try to evade capture.

Chico and Harpo disguise themselves as barbers and shave off an officer's mustache while he sleeps. The prank disrupts the ship's routine and showcases the brothers' knack for untidy mischief. They escape before being caught.

Groucho and Chico lock the ship's captain in a closet and help themselves to his lunch. The stunt highlights the brothers' brazen humor and the crew's growing exasperation. The captain is left to deal with the unexpected humiliation.

Groucho hides in the closet of gangster Alky Briggs and his wife Lucille, and begins romancing Lucille. He is eventually discovered and threatened by Briggs, raising the stakes of their onboard capers. The moment blends crime with slapstick humor.

Briggs, impressed by Groucho's nerve, has Chico and Harpo act as bodyguards while he confronts rival mob boss Big Joe Helton. He provides them with loaded guns, which they promptly ditch in a bucket of water. The scene parodies gangster bravado aboard the ship.

Chico and Harpo disrupt a chess game and confiscate the board, taking it into Helton's stateroom along with his daughter Mary. Their interference helps destabilize Briggs's plan and sets up the confrontation with Helton. The stowaways' antics reshape the power dynamics on board.

After the disruption unsettles Briggs, he hires Chico and Harpo as his bodyguards. Groucho meanwhile offers his own protection services to Helton, who says he will think it over. The on-board alliances become a running joke as loyalties shift.

The ship docks in the United States and the stowaways realize they must steal passports to disembark. Zeppo swipes Maurice Chevalier's passport and demonstrates his singing mimicry. The plan is to blend into American life by impersonating a star.

The four cut in line at customs and Zeppo impersonates Chevalier, but the ruse falls flat. Chico, Groucho, and Harpo each attempt unconvincing Chevalier imitations, with Harpo attaching a phonograph to his back to mimic the singing. The crowd grows restless as the impersonations continue.

A man faints, and Groucho poses as a doctor, urging the crowd to gather around the unconscious man so he won't recover. Sailors remove the man on a stretcher, which turns out to be the four stowaways hiding under a blanket. The farce exposes the absurdity of wartime border formalities.

Helton throws a coming-out party for Mary, whom Zeppo met onboard. Groucho is reunited with Lucille at the party, while Chico plays piano and Harpo plays harp. The festivities bring the film's on-board romance into full view.

Briggs's men, posing as musicians, kidnap Mary and hold her captive in an old barn. The four stowaways and Helton pursue, hoping to rescue her. The chase heightens the danger of Briggs's criminal plot.

Zeppo engages in fisticuffs with Alky Briggs, while Groucho provides ringside commentary. The group closes in on the barn and engages in a chaotic rescue attempt to free Mary. The humor escalates as the fight spills into the open.

Mary is rescued by Zeppo, and Groucho quips about finding a needle in a haystack to punctuate the caper. The stowaways' antics end on a note of continued anonymity, with the characters referred to only as 'the stowaways' in the credits. The film wraps on their offbeat humor.