This is a lengthy, intricate and necessarily leisurely read. It is also a very absorbing one. Wartime London amidst the bombs and blackout makes a bleak but graphic canvas for murder, nascent Fascism and subversive intrigue. The two protagonists, Stratton and Diana - robust policeman and refined Secret Service recruit (loosely based on real life agent Joan Miller) - are believable and sympathetically drawn, and their widely differing milieux realistically portrayed. Indeed, one of the strengths of the novel is the way that Laura Wilson collates and blends the various professional fields, domestic contexts and social strata. The suave and seamy, the urbane and humdrum, crisp ruthlessness and crude thuggery are deftly manipulated to produce a thriller of compelling realism. The pace may be leisurely but the prose is delivered with clarity, style and punchy humour; and the auxiliary characters - such as M I 5 chief Forbes-James, or Diana's distasteful husband - are sharply defined. Blackmail, espionage, illicit sex, unexplained deaths - yes, these are the classic ingredients of crime fiction; but set against and woven into the heightened ethos of the London Blitz, they take on an additional frisson. Set in a world of complex ambiguity, the novel's ending is appropriately oblique and prepares the reader for fresh developments.