Nancy Drew and her father, Carson, have come to Philadelphia to attend a meeting of the Vidocq Society, a group dedicated to the investigation of unsolved crimes. One of Carson's clients, Buff Bellamy, was recently tried for the slaying of Laurel Kenway, the ward of his uncle, real estate king Stafford Bellamy. Carson managed to get his client off on a technicality, but everyone-- except the Drews-- believes Buff got away with murder. Nancy's out to prove his innocence... beyond a question of a doubt.

Meanwhile...

Frank and Joe Hardy, and their father, Fenton, have come to the same meeting. Why? To prove beyond a doubt that Buff is guilty. Fenton investigated the crime, and the brothers found the evidence that convinced the district attorney to bring Buff to trial. It's a high-profile case in which Nancy, Frank, and Joe all have something to lose. But they all want the same thing. To find the real killer...