The four Marx Brothers star in their first film written specifically for the screen as stowaways on an ocean liner bound for New York. Each of them has a separate adventure on board; from matinee idol Zeppo's romancing of a bootlegger's daughter to Groucho having to avoid the attentions of gangster's moll Lucille Briggs.
Successful movie director John L. Sullivan (Joel McCrea), convinced he won't be able to film his ambitious masterpiece until he has suffered, dons a hobo disguise and sets off on a journey, aiming to "know trouble" first-hand. When all he finds is a train ride back to Hollywood and a beautiful blonde companion (Veronica Lake), he redoubles his efforts, managing to land himself in more trouble than he bargained for when he loses his memory and ends up a prisoner on a chain gang.
Fifth Avenue socialite Irene Bullock needs a forgotten man to win a scavenger hunt, and no one fits that description more than Godfrey Park, who resides in a dump by the East River. Irene hires Godfrey as a servant for her riotously unhinged family, to the chagrin of her spoiled sister, Cornelia, who tries her best to get Godfrey fired. As Irene falls for her new butler, Godfrey turns the tables and teaches the frivolous Bullocks a lesson or two.
It's no accident when wealthy Charles (Henry Fonda) falls for Jean (Barbara Stanwyck). Jean is a con artist with her sights set on Charles' fortune. Matters complicate when Jean starts falling for her mark. When Charles suspects Jean is a gold digger, he dumps her. Jean, fixated on revenge and still pining for the millionaire, devises a plan to get back in Charles' life. With love and payback on her mind, she re-introduces herself to Charles, this time as an aristocrat named Lady Eve Sidwich.
Burlesque barroom singer Lady Lou (Mae West) knows everyone in town, especially the men. Unfortunately, her convict ex-boyfriend Chick Clark (Owen Moore) is the jealous type and vows violence against her if she behaves unfaithfully while he's in prison. To make matters worse, Lou's boss, Gus Jordan (Noah Beery Sr.), secretly runs a prostitution and counterfeiting ring, and the director of the city mission next door is actually a federal agent (Cary Grant). What's a girl to do?
Hugo Hackenbush (Groucho Marx) is a veterinarian who masquerades as a lead doctor at Standish Sanitarium to aid the wealthy patient Emily Upjohn (Margaret Dumont). In order to save the financially failing sanitarium and its beautiful owner, Judy Standish (Maureen O'Sullivan), Hackenbush, employee Tony (Chico Marx) and jockey Stuffy (Harpo Marx) must find ingenious ways to help Gil Stewart (Allan Jones) and his inept racehorse, Hi-Hat, win the big race.
This screwball comedy finds married couple Tom (Joel McCrea) and Gerry Jeffers (Claudette Colbert) in a strained relationship, largely due to financial difficulties. Gerry decides to leave Tom, a struggling architect, and head to Palm Beach in order to marry a wealthy man who could fund Tom's projects. When Tom follows Gerry, they cross paths with the quirky millionaire John D. Hackensacker III (Rudy Vallee) and his chatty, husband-seeking sister, Princess Centimillia (Mary Astor).
Charles Bonnet (Hugh Griffith) expresses his passion for art by forging masterpieces -- and selling them at a hefty profit. The trouble starts when his reproduction of a prized sculpture winds up in a famous Paris museum. If experts determine that it is inauthentic, Bonnet's reputation will be tarnished. That's why his fetching daughter, Nicole (Audrey Hepburn), hires cat burglar Simon Dermott (Peter O'Toole) to steal the sculpture back before it's too late.
Mame Dennis (Rosalind Russell), a progressive and independent woman of the 1920s, is left to care for her nephew Patrick (Jan Handzlik/Roger Smith) after his wealthy father dies. Mr. Babcock (Fred Clark), Patrick's assigned executor, objects to Mame's unconventional way of living and tries to force her to send Patrick to prep school. As Mame and Patrick grow closer, Mr. Babcock tries to discipline Patrick and threatens to separate the two if Mame does not comply with his wishes.
Harried paleontologist David Huxley (Cary Grant) has to make a good impression on society matron Mrs. Random (May Robson), who is considering donating one million dollars to his museum. On the day before his wedding, Huxley meets Mrs. Random's high-spirited young niece, Susan Vance (Katharine Hepburn), a madcap adventuress who immediately falls for the straitlaced scientist. The ever-growing chaos -- including a missing dinosaur bone and a pet leopard -- threatens to swallow him whole.
