Richard Sherman, Tom Ewell, a middle-aged publishing executive in New York City, watches as his wife Helen Sherman and their son Ricky Sherman spend the summer in Ogunquit, Maine to escape the city’s crippling heat. When he returns home from the train station with the kayak paddle Ricky left behind, he meets an unnamed woman, Marilyn Monroe, who is a commercial actress and former model. She has subleased the apartment upstairs while its owners are away for the season. That evening, he resumes reading the manuscript of a book in which Dr. Brubaker claims that almost all men are driven to have extra-marital affairs in the seventh year of marriage. Richard 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 potted tomato plant falls onto his lounge chair; the seemingly unclad attractive young woman upstairs apologizes for accidentally knocking it off her balcony, and Richard invites her down for a drink. While waiting for her to arrive, he vacillates between a fantasy of her as a femme fatale overcome by his playing of Rachmaninoff’s Second Piano Concerto, and guilt at betraying his wife. When she appears, she is wearing pink pajamas and turns out to be a naïve and innocent young woman who works as a television toothpaste spokeswoman and recently appeared—highly enticingly—in a popular photo almanac. After repeatedly viewing her revealing pose his overactive imagination begins to run wild. On his suggestion, she brings back a bottle of champagne from her apartment and returns in a seductive white dress. Richard, overcome by his fantasies, awkwardly grabs at her while they are playing a “Chopsticks” duet on the piano, toppling them off the piano bench. He apologizes, but she says it happens to her all the time. Guilt-ridden, he asks her to leave.
Richard worries that Helen will find out about his transgression the following day at work, even though she is unaware of it and only wants Richard to send Ricky his paddle. Dr. Brubaker arrives at his office to discuss the book but is of no help. When Richard keeps hearing of his wife spending time with her attractive, hunky writer friend McKenzie in Maine, he imagines they are carrying on an affair; in retaliation, he invites the young woman out to dinner and a film. They go see Creature from the Black Lagoon in air-conditioned luxury. As the two chat while walking home, she briefly stands over a subway grate to enjoy its updraft, creating the iconic Monroe scene in her pleated white halterneck dress, her skirt blowing up in the breeze. He then invites her to spend the night at his air-conditioned apartment so she can rest up and look her best for the next day’s television appearance, with him on the couch and her in his bed.
In the morning, Richard argues with then assaults the man he imagined was having an affair with his wife in Maine. After knocking him cold, he comes to his senses and, fearing his wife’s retribution (within his dream), tells the woman she can stay in his apartment while he leaves to catch the train for two weeks in Maine.
