When the young heiress Gwendolen Ocumpaugh disappears from her family's estate, the shock spreads through New York society. Known as "the Millionaire Baby," the child is the cherished daughter of wealthy parents and the subject of an enormous reward. But her disappearance is no simple accident, and every clue seems to lead deeper into a maze of fear, secrecy, and hidden motives. Private detective Robert Trevitt sees in the case a chance to restore his fortune and reputation, but what begins as a search for a missing child soon becomes a psychological mystery involving family history, buried guilt, and dangerous deception. As suspicion falls across those closest to the child, Trevitt must decide who can be trusted before the truth is lost forever. First published in 1905, The Millionaire Baby is a richly atmospheric classic mystery from Anna Katharine Green, one of the pioneering figures of American detective fiction.