When an old friend is brutally murdered by the unlikeliest of assailants, Sarah Tanner is the only witness. Unable to turn to the police, she reluctantly finds herself drawn back into the dark underworld of the Victorian metropolis. Assisted by unlikely friends, dogged by the criminal machinations of 'the greatest gamester, felon, villain, swindler, and scoundrel in London', she must unravel a web of treachery and deceit, that takes her from the gaming hells of Regent Street to the suburban heights of Upper Holloway and beyond.