A madman is pushing people under Tube trains. Adam Buckley thinks he knows who it is, but has problems of his own to deal with. Damaged from a recent break-up, his narcolepsy worsening, he learns that his friends have become suicidally obsessed with finding insane, unexplored parts of London. He glimpses figures in the subterranean gloom, half-recognized faces at parties to which he can't remember being invited, indications of a life lived yet never remembered. As his confusion deepens, so too does the threat of violence. In peeling back so many of the city's faces, he fears that the skull beneath its skin might well be known to him.