The Notting Hill Mystery was first published between 1862 and 1863 as an eight-part serial in the magazine Once a Week. Widely acknowledged as the first detective novel, the story is told by insurance investigator Ralph Henderson, who is building a case against the sinister Baron R-, who is suspected of murdering his wife. Henderson descends into a maze of intrigue including a diabolical mesmerist, kidnapping by gypsies, slow-poisoners, a rich uncle's will and three murders. Presented in the form of diary entries, letters, chemical analysis reports, interviews with witnesses and a crime scene map, the novel displays innovative techniques that would not become common features of detective fiction until the 1920s.