Research chemist Barnaby Fulton works on a fountain of youth pill for a chemical company. One of the labs chimps gets loose in the laboratory and mixes chemicals, but then pours the mix into the water cooler. When trying one of his own samples, washed down with water from the cooler, Fulton begins to act just like a twenty-year-old and believes his potion is working. Soon his wife and boss are also behaving like children.
Cary Grant is the professor "Fulton" working for "Oxley" (Charles Coburn) on a project to find some way of turning back time and reversing the ageing process. They are experimenting with various formulae on a selection of rather agile chimps, and it's actually one of them who manages to co come up with a solution that when, inadvertently, added to the water in the cooler manages to turn the academic into a small child. He also feels a bit like a new man, too! This wears off after a short while, so he gets his wife "Edwina" (Ginger Rogers) to sit in on his next experiment - only this time he takes an even stronger dose. Except, he thinks it's his prescribed doses that are causing his youthfulness, whereas we know it's the water in the communal bottle - and that isn't anywhere near as restricted as his medication. Add to the mix, an on-form Marilyn Monroe and loads of daft baby talk and we are left with an enjoyable, if maybe just a little too repetitive, look at the child in all of us. There's a paint fight, some rubber band pranking and maybe neither Grant nor Monroe should ever have got into the car mid-way through. Coburn was always a master at the understated contribution, and here he is a perfect foil for the silliness of the plot as the story gathers pace and heads into the realms of plain screwball. Grant had comedy timing in spades, and with Rogers and Monroe showing they, too, were never far off the pace this is good fun to watch.