Wasps' Nest

Hercule Poirot visits his friend John Harrison and says that he is in the area to investigate a murder which has not yet been committed. Poirot then mentions a wasps' nest on a nearby tree and says that Harrison should destroy it. Harrison tells Poirot that a friend, Claude Langton, is arriving at 9pm to destroy the nest using petrol injected via a garden syringe. Poirot asks why not use cyanide of potassium, a deadly poison, instead, to which Harrison remarks that it is 'a risk having it about the place'. Poirot notes that he knows Langton bought cyanide of potassium, and wonders why. Poirot then asks 'Do you like Langton?', which surprises Harrison and leads to talk of Harrison's engagement to Molly Deane, who was previously engaged to Langton.

Poirot returns just before 9pm to find Langton leaving and the wasps' nest still intact. Poirot tells Harrison that he knows Harrison lied to him. The 9pm meeting was actually arranged for 8.30pm. Poirot had previously witnessed the signs of Langton's romance with Molly Deane being rekindled and, separately, Harrison leaving a Harley Street consultant having obviously been given bad news. Harrison confirms that he has two months to live. Poirot surmises that Harrison was planning to commit suicide and make it appear that Langton had killed him, ensuring that his rival would be hanged for murder. Furthermore, it was Harrison who asked Langton to buy cyanide of potassium. Harrison was planning, unbeknownst to Langton, to poison himself when the two men were alone. Having realised and repented of what he would have done, Harrison expresses his gratitude for Poirot having visited and spoiled his plans.