Nancy, Bess, and George investigating a mysterious boy from India. The lad, Coya, works for a traveling circus, and is treated poorly by his guardian, Rai, a mystic and elephant trainer, also a native of India. Rai gives Nancy an unusual hand-carved ivory elephant charm after she is nearly suffocated by an escaped snake.

Coya runs away from his abusive guardian and seeks shelter at the Drew home in River Heights. Soon after, the girls begin investigating property owned by the unusual Miss Allison. They encounter a house "with no insides," and a hidden tunnel. After the property mysteriously catches fire, a hidden cache of jewels is discovered. Nancy traces Coya's parentage and uncovers a sinister kidnapping plot involving both the American Miss Allison and Rai. The climax also reveals a secret about the Ivory Charm, and its mysterious powers.