Fitzwilliam, recently retired from a police career in Asia, by chance meets a lady on the train to London. He dismisses her talk of a murder as nonsense, until he reads of her death in the paper the next morning.

Murder is easy when it appears to be no more than a series of unrelated, fatal accidents. Mrs. Pinkerton meets Luke Fitzwilliam, a retired police officer, and tells him of a string of deaths in her hometown which she believes to be murders. Initially dismissive, he becomes intrigued when Mrs. Pinkerton is killed in a hit-and-run accident and the man she claims would be the next victim turns up dead. Can Luke find the murderer before another person, perhaps even himself, becomes the next victim?