Standing alone in the bleak Yorkshire Moors is Sir Rufus Marne's 'House of the Bears'. Dr. Palfrey is asked to journey there to examine an invalid - who he finds has disappeared. Moreover, Marne's daughter lies terribly injured after a fall from the minstrel's gallery, which Dr. Palfrey discovers was no accident. He sets out to look into both matters, but the discoveries he makes are truly fantastic. A deserted mine, powerful explosive and a submarine all feature in this powerful mystery. The results are even capable of surprising him ....