Carol Scott stumbles onto two mysteries quite by accident when first, during a Mardi Gras parade, she is given the strange jade shadow stone when she is mistaken for someone else. A short time later, Carol is once again mistaken for another person, Sonia and Seenia Mercier's niece, Angela, and at Sonia's request, Carol is asked to masquerade as the niece so that Seenia's poor health will not be stressed by the mistake.
Later that night, Carol meets the Mercier sisters' lawyer, Barry DeForest, who is highly interested in the shadow stone. He tries to convince Carol to give it to him to add to his collection. Carol instinctively distrusts the man.
Carol's two mysteries become connected when she once again visits the Mercier sisters and finds that their niece Angela has arrived, but the girl is connected with the mysterious shadow stone. Is the girl an imposter? And, is DeForest is cheating the sisters out of their fortune? Carol vows to discover the truth.
Writing under Stratemeyer Syndicate pen name Carolyn Keene from 1929 to 1947, she contributed to 23 of the first 25 originally published Nancy Drew mysteries. She was one of 28 individuals who helped produce the Syndicate's Nancy Drew mystery books from 1929 to 1984.
Edward Stratemeyer hired Benson in 1926. She was paid a flat fee of $125 for the first Nancy Drew book written using an outline provided by the syndicate.
The story wasn't bad but it was very predictable and the reader will have figured out the whole mystery by around 30 pages in. So for most of the book you are waiting for the characters to catch up to you. Also like other Wirt books it is crammed with racial stereotypes and villains, much more so than her contemporaries works.