Ten days' wonder

the long version

Howard Van Horn, son of millionaire Diedrich Van Horn, comes to Ellery Queen with the request that Ellery investigate what Howard has been doing during a recent bout with amnesia. The trail leads to the small New England town of Wrightsville and what seems to be a love triangle with Howard's stepmother, the beautiful young Sally, from the "wrong side of the tracks" in class-conscious Wrightsville. A series of small and unusual crimes over the next nine days seem to be committed by Howard during amnesiac blackouts, and Ellery Queen suddenly realizes the bizarre pattern that underpins the series of crimes. But it is only after the murder of one Van Horn and the suicide of another that Ellery Queen can reveal the true pattern underlying events and bring a crime home to the criminal.