A murderer challenges Poirot when he murders three unrelated people and leaves an open ABC railway guide showing the murder location. If you like Christie then you'll like this. She proves that if she had ever turned to a life a crime, no one would have been able to catch her--except, of course, Poirot.
- The perfect murder that Poirot describes became Cards on the Table which Christie published the same year as ABC. I haven't read it yet, but talk about a great way to publicize your next book.
- Poirot also reflects on a case where he brought to two people who loved each other together by arresting one for murder, is a reference to The Mysterious Affair at Styles, which I haven't yet read.