Roger Livesey ("Paul") is the wealthy but rather indifferent dad to "Dick" (Anthony Newley). The youngster hates the idea of going back to his boarding school, but his skinflint of a father is having none of it. When "Dick" tries a bit of emotional blackmail, his dad - clutching a mysterious stone from a temple in faraway India finds himself making a wish and now has the mental age of his son. His son, seeing an opportunity for some mischief takes hold of the stone and is soon his father in the body of a boy! What now ensue are an entertaining series of escapades as the youngster goes back…