In the small hours of the morning one fall day in 1866, a frantic widow visits detective Charles Lenox, Lady Annabelle's problem is simple: her beloved son, George, has vanished from his room at Oxford. When Lenox visits his alma mater to investigate, he discovers a series of bizarre clues, including a murdered cat and a card cryptically referring to the September Society. Then, just as Lenox realizes that the case may be deeper than it appears, a student dies, the victim of foul play. What could the September Society have to do with it?