Cary Grant portrays Fulton, a professor collaborating with Oxley (Charles Coburn) on an attempt to reverse aging. Their work involves testing different formulas on chimpanzees, and surprisingly, one of these primates discovers a potential solution. When accidentally mixed into the cooler’s water, it transforms the academic into a child, though he initially experiences a sense of renewed vitality. This effect is temporary, prompting him to involve his wife, Edwina (Ginger Rogers), in another experiment using a more potent dose. Unaware that his youthful appearance stems from the shared water bottle rather than his medication, he attributes it to his prescribed drugs. The film also features Marilyn Monroe and incorporates plenty of childish babble, resulting in an entertaining experience, although perhaps slightly repetitive at times. Scenes include a paint fight, playful rubber band tricks, and moments where Grant and Monroe’s presence in a car seems ill-advised. Coburn excels with his subtle performance, serving as a perfect contrast to the plot's absurdity as the story progresses into pure screwball comedy. Grant demonstrates impeccable comedic timing, supported by Rogers and Monroe, who also prove their comedic abilities throughout the film, making for an enjoyable viewing experience.

Source on TMDB