Nicky Ferrante, a well-known playboy, and Terry McKay, a nightclub singer, meet aboard an ocean liner traveling from Europe to New York. Despite both being engaged to other people, they develop a strong connection and begin to fall deeply in love during the voyage. As the ship approaches its destination, they agree to test their feelings by giving themselves six months to settle their respective lives and meet again at the top of the Empire State Building if they still feel the same way about each other. This agreement symbolizes their commitment to find out if their relationship can withstand the trials of the real world and not just the fleeting romance of a vacation cruise.

Back in New York, Nicky pursues a career change from frivolous society life to becoming a serious painter, while Terry returns to her job, grappling with her deepening affection for Nicky despite her existing engagement to a wealthy businessman. Each of them faces numerous challenges and undergoes significant personal growth, which tests their resolve and dedication to the promise they made. These experiences shape their perspectives on love, life, and destiny, leaving them eagerly anticipating the appointed rendezvous to discover if their love was meant to be.