A black-robed ghost roams the streets of the Danas' home town. A tiger stalks the woods on the outskirts of Oak Falls. And the Hilary Museum is plagued by a phantom prowler who seemingly passes through locked doors and windows.

Louise and Jean Dana, returning home from a long trip, are horrified by these events. Their friend Elise Hilary begs them to solve the mystery surrounding the private museum. Elise, however, can volunteer no clue to what the ghostlike intruder is searching for, nor can she offer any clue to the sender of a threatening note.

Center of the sinister conspiracy is the magnificent marble tiger presented to the museum by a maharajah. Its eyes glow by night, the black-robed ghost attempts to mutilate it, and the sound of flute music floats eerily from somewhere in the museum.

Determined to unravel the spooky puzzle, Louise and Jean involve themselves in some frightening adventures as they follow a maze of clues to the solution of this suspense-filled mystery.