A dying woman, Mrs Davis, gives her last confession to an elderly priest, Father Gorman. Along with her confession, she gives him a list of names and a terrible secret. Before he can take action, he was murdered.
Mark Easterbrook, the hero of the book and its principle narrator learns of an old inn called The Pale Horse, inhibited by three modern witches. Behind the appearance of witchcraft playing on people’s psychology, the actual answer to the natural death of those people being bet to died on lies in the simple answer of thallium poisoning.
This novel is notable amongst Christie’s books as it is credited with having saved at least 2 lives after readers recognised the symptoms of thallium poisoning from its description in the book.
Thallium is a soft, malleable gray metal that was previously widely used in rat poisons and insecticides. In the first 48 hours after serious thallium exposure, the affected individual will usually experience nausea, vomitting and diarrhoea. Within a few days, symptoms of nervous system damage become apparent. These symptoms can include pain, loss of reflexes, convulsions, muscle wasting, headaches, numbness, dementia, psychosis and even coma. After 2-3 weeks, characteristic changes are seen in the bases of hair shalfs, and there is hair loss. Finally after around 3 weeks post-exposure, heart rhythm disturbances may occur.
Thallium poisoning can be treated.
From this novel, it tells that murder can be very simple and clean, which is quite scary.