Monk is commissioned to find the stolen ivory from the hold of Clement Louvain’s  ocean-going schooner.  The river Thames – ‘the longest street in London’- is new territory for Monk, and without the help of the River Police, he does not stand a chance of finding the thief, or even of keeping his own life.  Hester’s clinic admits a woman with a mysterious connexion to Louvain.  We meet, for the first time, the street-wise Cockney orphan, Scuff, who will feature more in the lives of Hester and Monk.