On a spring morning in 1840, on an ultra-respectable Mayfair street, a household of servants awoke to discover that their unobtrusive master, Lord William Russell, was lying in bed with his throat cut so deeply that the head was almost severed. The whole of London, from monarch to maidservants, was scandalized by the unfolding drama of such a shocking murder, but behind it was another story, a work of fiction. For when the culprit eventually confessed, he claimed his actions were the direct result of reading the best-selling crime-novel of the day. This announcement amazed the key literary figures of the time, from Thackeray to Dickens, and posed the question: can a work of fiction do real harm?