Baker Street Boys:The Case of the Captive Clairvoyant by Anthony Read
Holmes and Watson are out of town and it's up to the Boys to rescue Mary from the clutches of her evil stepfather, Marvin the Mystic. But Marvin is in cahoots with the dastardly Moriarty! Together they scheme to rob rich people's houses while Marvin performs seances. The Boys know Mary will never be safe with Marvin on the loose, so they hatch a fiendish plan to catch the criminals...