A mysterious brass-bound trunk delivered to the wrong cabin on an ocean liner pulls Nancy Drew into a high-stakes investigation involving international jewel thieves. Nancy must navigate the confined, opulent environment of a New York-bound ship while attempting to identify the criminals hiding among the passengers. She faces the challenge of gathering evidence without alerting the perpetrators, who are prepared to use force to protect their illicit cargo. The narrative follows a classic mystery structure, utilizing a third-person perspective to track Nancy's deductive reasoning and her interactions with suspicious travelers.

This title remains a staple of the long-running Nancy Drew series, reflecting the enduring appeal of the character's investigative prowess. The revised version is often noted for its streamlined pacing, which caters to a younger audience while maintaining the core elements of the original mystery. Readers frequently highlight the atmospheric setting of the ocean liner as a key component that heightens the tension of the investigation. The book is generally regarded as a quintessential example of mid-century juvenile detective fiction that continues to influence the genre today.