You belong to me - Mary Higgins Clark

Regina Clausen was forty-three, successful in her career but insecure and unfulfilled in her personal life. Travelling alone on the luxury liner Gabrielle, she disembarked in Hong Kong saying she would rejoin the ship when it docked in Japan. She was never seen again. . . Three years later, radio presenter Susan Chandler does a series about vanishing women on her radio talk show. When a caller, who refuses to identify herself, tells of meeting a man on a cruise who gave her a ring inscribed 'You Belong to Me', but then disappeared when she refused to leave the ship with him, she thinks little of it. But then Regina's mother appears at Susan's office with a ring bearing the same inscription which was found amongst her daughter's belongings, and Susan begins to suspect that they are on the trail of something dangerously sinister...