Fresh out of high school, Gregory Williamson arrives in Nantucket in the summer of 1946 for a job as a night watchman at a local hotel. He meets Sydney MacKluskie, a beautiful and sophisticated World War II widow, who works as the dining room hostess. The two become close, playing tennis together and talking in the evenings. After Greg saves Sydney from a rapist, the two plunge into an intimate relationship.

Because of their age difference, Sydney suddenly leaves Nantucket and returns to Chicago to continue her studies in the medical profession. Heartbroken, Greg struggles to come to terms with her absence. He plays basketball at Purdue University, enrolls in the army's ROTC program, and graduates from college with a commission as a second lieutenant.

But with the start of the Korean War, Greg is called to active duty and shipped overseas. When he is severely wounded, a skilled female surgeon saves his life. Was that surgeon Sydney? Greg is determined to find out. Will his search be successful, or will he forever wonder about Sydney and what might have been?