Agatha Christie: The Mysterious Affair at Styles

CHAPTER 13. POIROT EXPLAINS (continued)

"Bon! I will reconstruct for you as far as possible. I am inclined to think that Miss Howard was the master mind in that affair. You remember her once mentioning that her father was a doctor? Possibly she dispensed his medicines for him, or she may have taken the idea from one of the many books lying about when Mademoiselle Cynthia was studying for her exam. Anyway, she was familiar with the fact that the addition of a bromide to a mixture containing strychnine would cause the precipitation of the latter. Probably the idea came to her quite suddenly. Mrs. Inglethorp had a box of bromide powders, which she occasionally took at night. What could be easier than quietly to dissolve one or more of those powders in Mrs. Inglethorp's large sized bottle of medicine when it came from Coot's? The risk is practically nil. The tragedy will not take place until nearly a fortnight later. If anyone has seen either of them touching the medicine, they will have forgotten it by that time. Miss Howard will have engineered her quarrel, and departed from the house. The lapse of time, and her absence, will defeat all suspicion. Yes, it was a clever idea! If they had left it alone, it is possible the crime might never have been brought home to them. But they were not satisfied. They tried to be too clever--and that was their undoing."

Poirot puffed at his tiny cigarette, his eyes fixed on the ceiling.

"They arranged a plan to throw suspicion on John Cavendish, by buying strychnine at the village chemist's, and signing the register in his hand-writing.

"On Monday Mrs. Inglethorp will take the last dose of her medicine. On Monday, therefore, at six o'clock, Alfred Inglethorp arranges to be seen by a number of people at a spot far removed from the village. Miss Howard has previously made up a cock and bull story about him and Mrs. Raikes to account for his holding his tongue afterwards. At six o'clock, Miss Howard, disguised as Alfred Inglethorp, enters the chemist's shop, with her story about a dog, obtains the strychnine, and writes the name of Alfred Inglethorp in John's handwriting, which she had previously studied carefully.