Holmes eventually makes an appearance, having been hiding in the vicinity for some time making his own investigation. An effective scene, not in the original book, occurs when Watson and Sir Henry attend a seance held by Mrs. Mortimer (Beryl Mercer). In a trance, she asks, "What happened that night on the moor, Sir Charles?" The only reply is a lone howl, possibly from a hound. After some clever deception by Holmes, he surmises that the true criminal is Stapleton, a long-lost cousin of the Baskervilles, who hopes to claim their vast fortune himself after removing all other members of the bloodline.