Montmorency, the man leading a double life, torn between his two identities, returns in this gripping sequel. Five years after giving up his life of crime in the sewers, Montmorency is back in London. But his evil alter ego, Scarper has returned too, pulling him back into a dark world of crime. Montmorency's old friend and fellow government agent, Lord George Fox-Selwyn, fights to rescue him from disaster and risks calling in Montmorency's prison doctor, Robert Farcett, to help. However, when Montmorency turns up on a Scottish Island, he finds himself caught in another web of mystery.