The Disappearing Floor

When a notorious jewel thief and their accomplices go on the run, the Hardy Boys are called in to help their detective father. The case takes a strange turn when the trail leads to a heavily guarded mansion on the old Perth estate, where a mysterious death has occurred. With their friend Chet Morton by their side, Frank and Joe must solve the secrets of the mansion, including a disappearing floor and a phantom hound, to catch the criminals.