The Jorgensons are a wealthy family spending the summer on a resort island. Ken (Richard Egan), Helen (Constance Ford) and daughter Molly (Sandra Dee) settle in to a beach house on the island where Ken was a young lifeguard twenty years ago. He rediscovers Sylvia (Dorothy McGuire), with whom he had an earlier affair before she married Bart Hunter (Arthur Kennedy). The Hunter's son Johnny (Troy Donahue) and Molly fall in love, much to the objection of her mother, a cold and cynical woman. When Ken and Sylvia start another torrid affair, the exposure of the liaison leads to the divorce of both married couples. After Johnny and Molly are stranded overnight on a beach, Molly is forced by her heartless mistrusting mother to undergo a physical examination and a pregnancy test. Tests results are negative, but more negative is the mother-daughter relationship. Ken and Sylvia get married and Molly gets pregnant. The newlyweds then compassionately guide unwed couple to marriage.
by Dan Pavlides synopsis