Tacey and Harry King are a suburban couple with three sons and a serious need of a babysitter. Tacey puts an ad in the paper for a live-in babysitter, and the ad is answered by Lynn Belvedere. But when she arrives, she turns out to be a man. And not just any man, but a most eccentric, outrageously forthright genius with seemingly a million careers and experiences behind him. Mr. Belvedere works miracles with the children and the house but the Kings have no idea just what he's doing with his evenings off. And when Harry has to go out of town on a business trip, a nosy parker starts a few ugly rumors. But everything comes out all right in the end thanks to Mr. Belvedere. 壁立千仞，无欲则刚。 哈里（罗伯特·杨 Robert Young 饰）同妻子与三个孩子居住在风景宜人的郊区，繁忙的工作让他无暇照顾孩子们，面对三个整天调皮捣蛋的臭小子，哈里的妻子（玛琳·奥哈拉 Maureen O'Hara饰）亦感到力不从心，请一位能够帮忙又不会添麻烦的保姆似乎成为了哈里唯一的选择，就这样，一个名叫贝尔维德尔（ 克利夫顿·韦伯 Clifton Webb饰 饰）的人成为了保姆的最终人选。 直到贝尔维德尔入驻哈里的家中之后，哈里才发现，这个表面看来温柔的人其实是一个怪人，但是，神奇的是，他用不知道是哪门子的怪招，竟然将哈里的三个儿子给管教得服服帖帖，这让哈里不得不服。随着时间的推移，外界开始有了一些关于贝尔维德尔的不堪传言，这些传言究竟是不是真的呢？
