Two bodies are discovered on the same night in the same part of London: both shocking, both inexplicable - neither entirely human.Police Commissioner Sir Richard Mayne's prized Detective Force is being mocked by the press on one side and investigated by Parliament on the other. His notorious investigator Inspector Albert Newsome seems afflicted by a dangerous mania and Sir Richard himself is expected to stand before parliament to defend the practices of his men. So when two houses are apparently burned down by an incendiary, the commissioner sees an opportunity to again recruit the victims of the crime: ex-detective George Williamson and his shadowy friend Noah Dyson.Together, they are obliged to collaborate in a case more gruesome and extraordinary than any of them has experienced. Further inhuman effigies appear, Scotland Yard itself is robbed, Mr Williamson is arrested for murder, and men walk the streets wearing the exact likenesses of others. Is the evil mind behind this chaos the same man being sought by Inspector Newsome? And is the villain's aim blackmail, revenge, anarchy . . . or merely terror? In this city of many faces, voices and guises, how can any man be recognised as one's lethal adversary?