The Valley of Fear

A coded warning from an informer inside Professor Moriarty's organisation reaches Baker Street too late: a man named John Douglas has been found shot in his moated manor house at Birlstone. Holmes and Watson investigate a locked-room puzzle full of strange details, a missing dumbbell, a wedding ring taken from the victim's finger, and a card bearing the letters V.V. 341.

Published in 1915, this is the last of the four Holmes novels. Like A Study in Scarlet, it moves halfway through to America, here to the coal valleys of Pennsylvania and a secret society inspired by the real Molly Maguires, with a tense undercover story that many readers think the best part of the book.

Arthur Conan Doyle (1859–1930) was born in Edinburgh, trained as a doctor and wrote stories while waiting for patients at his practice in Southsea. Sherlock Holmes, modelled partly on his old teacher Joseph Bell, who could diagnose a patient's life at a glance, first appeared in 1887 and soon made Doyle one of the best-paid writers in the world.

He grew tired of his detective, killed him off in 1893 and was forced by his readers to bring him back. Doyle also wrote historical novels, the adventure The Lost World and campaigns for wrongly convicted men. Start with The Adventures of Sherlock Holmes and The Hound of the Baskervilles.