Lawyer Harry King (Robert Young (actor)) and his wife Tacey (Maureen O'Hara) have trouble retaining a nanny for their three young, rambunctious boys. When the latest in a string of servants (all women) quits, Tacey advertises for a replacement and hires Lynn Belvedere sight unseen, only to later discover that Lynn is a dapper gentleman (Clifton Webb), one with many skills and achievements. Despite their misgivings (and Belvedere's declaration that he detests children), the Kings reluctantly agree to a trial period. Belvedere quickly wins over the boys, but his superior attitude annoys Harry.