Cynthia Glenn, Esther Williams, is a cheerful swimming instructor in Los Angeles who shares a home with her scatterbrained aunt Nona Glenn Spring Byington and her practical uncle Hobart Glenn Henry Travers. While demonstrating a dive at a sunlit pool, she catches the eye of a dashing stranger, Bob Delbar [Carleton G. Young], who sends her flowers and soon wins her heart. After a month of courtship, the couple marries and sets off for a honeymoon that promises new beginnings.
On their getaway at the Monte Belva, they encounter the hotel’s famous opera singer, Nils Knudsen [Lauritz Melchior], whose presence adds a gilded touch to the resort. Major Thomas Milvaine [Van Johnson], another guest, notices Cynthia with a respectful curiosity that thickens the hotel’s social tapestry. A wealthy colleague, J. P. Bancroft [Thurston Hall], pushes Bob to fly to Washington, D.C. to close a deal, leaving Cynthia unsettled as she watches him depart. Tommy, staying next door, offers quiet consolation to the newlyweds as Cynthia wrestles with loneliness and longing.
The next day by the pool, Bancroft’s daughter Maude [Frances Gifford] playfully speculates about Milvaine’s true identity, wondering which hotel guest is the war hero who supposedly shot down “16… or was it 26 war planes?” Her teasing about Cynthia’s bareness of being at the hotel without her husband nudges the couple toward an awkward bond. When Cynthia performs an elaborate, seemingly effortless dive, she accidentally crosses paths with Milvaine again, a man who cannot swim. She takes it upon herself to teach him, and their shared moments by the water deepen into a warm, tentative friendship that blooms through a week of dinners, swims, and other hotel adventures.
On the last day, Cynthia receives a telegram informing her that Bob cannot return for another week. Tommy is set to depart the next morning, and Cynthia, distraught, withdraws to her room. Tommy realizes his love and hurries to her adjoining balcony to declare it, but Cynthia holds firm to her marriage, insisting she will not betray it. She phones Bob, begging him to return, but he cannot. The two lovers’ disappearance on the Sunset Trail leads them to spend a night in the woods after losing their way, a turn that tests every vow they have made.
The following morning, Bob discovers his wife is missing and, upon their return, confronts the tangled emotions with a demand for an annulment. He learns that he was never legally divorced, a revelation that reshapes the conflict but does not instantly resolve it. Tommy leaves to become an instructor at Darwin Field, and Cynthia returns to the safety and nuance of her aunt and uncle’s home.
Late at night, Nils Knudsen calls again, and the trio—Cynthia, Tommy, and Knudsen—share a melody that drifts through the house. Tommy lip-synchs Knudsen’s voice to accompany a whispered plea of love, and when Cynthia steps outside, she finds Tommy waiting with a kiss as Knudsen’s singing continues in the background. The moment leaves Nona and Hobart both amused and quietly astonished at how romance, music, and fate can collide in such a small, sunlit corner of the world.
