Monkey Business

Monkey Business is a 1952 American screwball comedy film directed by Howard Hawks, written by Ben Hecht, and starring Cary Grant, Ginger Rogers, Charles Coburn, and Marilyn Monroe. To avoid confusion with the 1931 Marx Brothers film of the same name, this film is sometimes referred to as Howard Hawks' Monkey Business.

Plot
Dr. Barnaby Fulton (Cary Grant), an absent-minded research chemist for the Oxly chemical company, is trying to develop an elixir of youth. He is urged on by his commercially minded boss, Oliver Oxly (Charles Coburn). One of Dr. Fulton's chimpanzees, Esther, gets loose in the laboratory, mixes a beaker of chemicals, and pours the mix into the water cooler. The chemicals have the rejuvenating effect Fulton is seeking.

Unaware of Esther's antics, Fulton tests his latest experimental concoction on himself and washes it down with water from the cooler. He soon begins to act like a 20-year-old and spends the day out on the town with his boss's secretary, Lois Laurel (Marilyn Monroe). When Fulton's wife, Edwina (Ginger Rogers), learns that the elixir "works", she drinks some along with water from the cooler and turns into a prank-pulling schoolgirl.

Edwina makes an impetuous phone call to her old flame, the family lawyer, Hank Entwhistle (Hugh Marlowe). Her mother, who knows nothing of the elixir, believes that Edwina is truly unhappy in her marriage and wants a divorce.

Barnaby takes more elixir and befriends a group of kids playing as make-believe "Indians" (Native Americans). They capture and "scalp" Hank (giving him a Mohawk hairstyle), later fleeing when police show up. Meanwhile, Edwina lies down to sleep off the formula. Meanwhile, a woman leaves her baby with the Fultons' housekeeper as she needs an emergency babysitter. When Edwina awakens, a naked baby is next to her and Barnaby's clothes are nearby. She mistakenly presumes he has taken too much formula and regressed to a baby. She takes the child to Oxly to resolve the problem. Together the two attempt to find an antidote and when the baby grows sleepy, Edwina tries to put him to sleep in the hopes of reversing the effects.

Meanwhile, more and more scientists (and Mr Oxly) at the laboratory are drinking the water and reverting to a second childhood. The formula is lost with the last of the water poured away. As the water is poured away, Barnaby crawls into the laboratory through the window and lays down to sleep next to the baby. Edwina later discovers him and realizes her mistake with the baby. Later at home as Barnaby and Edwina are planning to go out, their spirits and marriage renewed, Barnaby notes that "you're old only when you forget you're young."

Cast

 * Cary Grant as Dr. Barnaby Fulton
 * Ginger Rogers as Edwina Fulton
 * Marilyn Monroe as Lois Laurel
 * Charles Coburn as Oliver Oxley
 * Hugh Marlowe as Hank Entwhistle
 * Henri Letondal as Dr. Jerome Kitzel
 * Robert Cornthwaite as Dr. Zoldeck
 * Larry Keating as G.J. Culverly
 * Douglas Spencer as Dr. Brunner
 * Esther Dale as Mrs. Rhinelander
 * George Winslow as Little Indian