Cyrus Barker, along with his former assistant and now partner Thomas Llewelyn, is the premier enquiry agent in all of 19th century London, and beyond. They've thwarted the designs of villains and crooks of all sorts, helped Scotland Yard crack their most challenging cases, and worked for the Her Majesty's Government at the very highest levels. But nothing has been quite as challenging and dangerous as the latest case that comes to find them.