Summer, 1840. Edgar Allan Poe arrives in London to meet his friend C. Auguste Dupin, in the hope that the great detective will help him solve a family mystery. For Poe has inherited a mahogany box containing sheathes of letters that implicate his grandparents in some of London's most heinous and scandalous crimes – those committed by the so-called London Monster who, for two years, terrorized the city's streets, stalking attractive, well-to-do young women, slicing their clothing and their derrières.

Unable, or perhaps unwilling, to accept that his grandparents – actors who struggled to make a living on the London stage – led a clandestine and nefarious double life, Poe and Dupin set out to prove the missives forgeries. But as they delve deeper into the city's secrets, and past horrors emerge, they start to suspect that they too are being watched and preyed upon. And if they are, might their stalkers be connected to the London Monster?