When Dr William Macbeth poisoned two of his sons in 1927, his wife and sister hid the murders in the intensely private realm of family secrets. Like the famous poisoner Dr Crippen, Macbeth behaved as if he were immune to consequences; unlike Crippen, he avoided detection and punishment … or did he?

As time passed, the story of Dr William Macbeth, well-dressed poisoner, haunted and divided his descendants. Macbeth’s granddaughter Gail Bell, who grew up with the story, spent 10 years reading the literature of poisoning in order to understand Macbeth’s life. A chemist herself, she listened for echoes in the great cases of the 19th and 20th centuries, in myths, fiction and poison lore.

This intricate story, with a moving twist at the end, is a book about family guilt and secrets, and also an exploration of the nature of death itself as Bell turns to her grandfather’s poisonous predecessors, from Cleopatra, Madame Bovary and Napoleon to prolific serial killer, Harold Shipman.