Arnold escapes from the kidnapper and makes it home, but leaves Kimberly behind and can't remember where she is. A policeman helps Arnold remember by hypnotizing him and getting him to reveal the license plate number of the kidnapper so the police can track him down to arrest him. 

David Hasselhoff rescues Arnold and Dudley just in time and the rest of the family find out about Mr. Drummond's marriage plans. Arnold is less than thrilled, especially when he finds out he's getting a new little brother as part of the deal.