The Swami's Ring — Carolyn Keene

When an amnesia victim arrives at Rosemont Hospital in River Heights, Nurse Lisa Scotti contacts her friend, Nancy Drew. The young man was found injured, at the bottom of a cliff, with no identification and no memory of what happened to him. A thorough search of his knapsack, however, turns up an unusual ring, much too large for the mysterious stranger to wear.

Learning that the ring is of Hindu origin, Nancy sets off on a trail of danger as she searches for the man's forgotten identity. Before long, she is caught up in another assignment. A plea from a beautiful harpist has Nancy looking for the troublemakers who are determined to boycott the River Heights Summer Music Festival. Nancy's discoveries reveal an important connection between the hospital patient, the harpist, and enemies from abroad.