The Mystery of Cloomber. Arthur Conan Doyle

This novel is narrated by John Fothergill West, who tries to discover why the tenant of Cloomber Hall, General Heatherstone, is nervous to the point of being paranoid. Why are his fears becoming stronger every year at the fifth of October? And why doesn't he let his children leave home? This is a great mystery novel with a sharp twist at the end.