The River Men — Gerald Verner

Twenty-seven robberies, fifteen cargo broaches, and seven cases of murder: not in the past fifty years has there been such an outbreak of thieving and crime on the Thames; and in no single instance has the culprit been brought to justice, or his identity discovered. A new criminal organization with a mystery man at its head is playing the London river police for fools - and the latest officer on the case has been murdered, his body weighted and sunk in the river. Such is the challenge facing Inspector Terry Ward...