Hughes Massie, asking him to keep a manuscript in reserve (probably Sleeping Murder) and statedI have been, once, in a position where I wanted to write just for the sake of money coming in and when I felt I couldn't – it is a nerve wracking feeling. If I had had one MS 'up my sleeve' it would have made a big difference. That was the time I had to produce that rotten book The Big Four and had to force myself in The Mystery of the Blue Train. Plot summary An unexpected visitor called Mayerling comes in through Hercule Poirot's bedroom and collapses on the floor. The only clue to what he wants is his repeating Poirot's name and address and writing the number 4, many times. When Hastings jokingly calls it "The Mystery of the Big Four," the man begins speaking about an international crime cartel of that name. He describes the four leaders: Number 1 is a Chinese political mastermind named Li Chang Yen; Number 2 is probably American; Number 3 is a Frenchwoman; and Number 4 is known only as "the Destroyer." The man dies soon after and Poirot and Hastings go off on the trail of the Big Four. From here, the novel becomes a series of loosely connected short stories. Poirot and Hastings visit an informant, John Ingles, to ask him about the Big Four. Ingles shows Poirot a note from a fisherman who asked him for a few hundred pounds to hide himself from the Big Four. Poirot, Hastings and Ingles discover that the man who wrote the note, a Mr Jonathan Whalley, has been murdered by Number 4. Poirot discovers that the Big Four have produced a form of wireless energy capable of focusing a beam of great intensity on any spot. A British scientist called Halliday was near success on this same concept when he was kidnapped while at a conference in France. Poirot and Hastings visit the notable French scientist Madame Olivier and discover she is Number 3. Poirot discovers that American millionaire Abe Ryland is Number 2 and sends Hastings to spy on him. Poirot investigates the death of a Mr Paynter in Worcestershire. Before his death, Paynter had written in ink "yellow jasmine" on his newspaper, and attempted to draw a number 4. Poirot reveals that Paynter's attending physician, a Doctor Quentin, was in fact Number 4, who