A doctor is summoned. An uninvited man arrives, claiming to work for a lunatic asylum and to be in search of an escaped inmate. He identifies the dead man as the escapee in question, then departs. Poirot calls the asylum and learns that there have been no recent escapes. Japp soon enters and recognises the dead man as Mayerling, a prominent figure in the Secret Service who had disappeared five years before. Poirot asks Hastings if he opened the windows, to which Hastings replies in the negative. Poirot examines the man and announces that Mayerling was gagged and poisoned by inhaling "prussic acid" (hydrogen cyanide). The hands of the lounge clock have been turned to 4 o'clock, and Poirot realises that the murderer was the man from the asylum. He was the Destroyer.