George Jeffries is attempting to guide a coach party of eccentrics around Scotland via the treacheous mountain known as The Devil's Elbow. But when one of the touring party is found dead, suspicion falls on the hapless Jeffries. His fiancee goes in tears to her employer, who happens to be the remarkable psychoanalyst and private investigator Mrs Bradley. Fortunately for all concerned Mrs Bradley takes the case, and employs all her singular talents in the task of finding the true murderer.