In a sunny and fun corner of California, a charming but scatterbrained daughter of a shipping magnate, played by Doris Day, works on an innovative glass-bottomed boat that allows its passengers to observe the fascinating underwater world. Her life takes an unexpected turn when she accidentally encounters a scientist, portrayed by Rod Taylor, who is researching marine life and has very different plans than hers. The attraction between them is instant, but the protagonist's life becomes complicated when he gets embroiled in a web of espionage.
The problem is that as their relationship develops, misadventures arise time and again. Her clumsiness leads her to be seen as a potential spy, resulting in a hilarious game of misunderstandings and chases. As they both try to untangle the truth behind the rumors surrounding them, they begin to uncover secrets not only about each other but also about themselves.
With a light and comedic touch, the entanglements lead to absurd situations where the hero's past and the protagonist's innocent life collide explosively. The film balances romantic comedy with elements of intrigue, all wrapped in a sunny and charismatic atmosphere, where love, confusion, and a bit of underwater adventure intertwine to create a story full of laughter and heart that will leave audiences feeling butterflies.