30 IS A DANGEROUS AGE, CYNTHIA!

London jazz pianist and aspiring composer Rupert Street is soon to turn 30 and fears reaching that age without having accomplished anything. To avoid this, he sets himself goals to marry a woman and write a musical. He meets the gorgeous but taken Louise, a fellow boarder, and pursues her in his goofy and inept manner. A fight with competing suitor Paul leaves Rupert with his right arm in a cast and unable to play the piano.

To avoid further distractions, Rupert travels to Dublin, where he finds success composing the musical, and he returns to London triumphant. However, his other goal is in jeopardy, as Louise has left for Birmingham with Paul.

In order to sign Rupert to a contract, the production's major investor forces his agent to send private eye Herbert Greenslade to Birmingham to find Louise. Reunited with Louise on his birthday, Rupert whisks her back to London to be married.

Rupert completes his musical and, after a chase to Birmingham, is reunited with Louise on his birthday. They rush back to London to marry just before the opening of his show.

The finale ties up Rupert’s dual quests, allowing him to achieve both artistic and romantic fulfillment at the last possible moment. It’s a comedic payoff that rewards his persistence and the film’s theme of seizing opportunity before it slips away, suggesting that achievement—and love—are sometimes a matter of timing, pluck, and a bit of luck.