Wilkie Collins' The Moonstone

Meanwhile in England, the seeds of the early detective story are found in the Victorian sensation novel, a subgenre that turns on the revelation of a secret. Murder, fraud, adultery, and secret identities are its main themes. Wilkie Collins' The Woman in White is considered to be the first of two genres: the mentioned sensation novel and the mystery novel.
But the author's later work indicates a move towards detective fiction. The Moonstone was the first novel to deal in detail with the legal, forensic, and police procedures surrounding the detective's investigation. The Moonstone was also unique in that it reflected new psychological theories and took the English colonization of India as its frame setting.

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