Ian Mackenzie is awakened at Kilmorgan Castle one night to find robbers stealing the priceless art collection of his oldest brother, Hart. Since Ian and Beth are the only ones in residence at Kilmorgan at the moment, Ian decides that he must find the art and the culprits before the family shows up for Hart's birthday gathering. With Inspector Fellows and Beth, he investigates, though Ian is somewhat worried by Beth's late husband's brother, a retired missionary, who decides to visit. Does John Ackerley hold the cure to Ian's madness? And can Ian discover what has happened to Hart's treasures and who is targeting the Mackenzies before the enemy strikes again?