A Is For Arsenic : The Poisons Of Agatha Christie

Agatha Christie revelled in the use of poison to kill off unfortunate victims in her books; indeed, she employed it more than any other murder method, with the poison itself often being a central part of the novel. Her choice of deadly substances was far from random - the characteristics of each often provide vital clues to the discovery of the murderer. With gunshots or stabbings the cause of death is obvious, but this is not the case with poisons. How is it that some compounds prove so deadly, and in such tiny amounts?