Richard Sherman (Tom Ewell) is a nerdy, faithful, middle-aged publishing executive with an overactive imagination and a mid-life crisis, whose wife, Helen (Evelyn Keyes), and son, Ricky (Butch Bernard), are spending the summer in Maine. When he returns home with the kayak paddle Ricky accidentally left behind, he meets a woman (Marilyn Monroe), who is a commercial actress and former model who rents the apartment upstairs while in town to make television spots for a brand of toothpaste. That evening, he works on reading the manuscript of a book in which psychiatrist Dr. Brubaker (Oskar Homolka) claims that almost all men are driven to have extra-marital affairs in the seventh year of marriage. Sherman has an imaginary conversation with Helen, trying to convince her, in three fantasy sequences, that he is irresistible to women, including his secretary, a nurse, and Helen’s bridesmaid, but she laughs it off. A tomato plant then crashes into his lounge chair; the woman upstairs apologizes for accidentally knocking it off the balcony, and Richard invites her down for a drink.