Smith crosses the line into brilliance.

Smith himself [is] a pickpocket by trade…. After he has taken—something—from a troubled-looking old gentleman, he sees his victim murdered and searched by two men in brown. His find is a document: but Smith cannot read…. The tale leaps on in a series of dazzling scenes—a session in Newgate where Smith is held for the old man's murder; an eerie flight through a kind of ventilator; the reading at last of the script; the tomb with the black stone angel to which it leads; the extraordinary climax. Leon Garfield speeds with shrewd or crackling or poignant wit through the London of dark thieves' kitchen and gentleman's mansion, in and out of St Paul's, St Andrew's and the Old Bailey. To follow is an electrifying experience. (pp. 732-33)