Corre el ano de 1864. En la ribera del Tamesis Monk queda consternado ante la espantosa mutilacion de una mujer cuyo cadaver es hallado en el embarcadero de Limehouse. Pero cuando investiga el brutal asesinato y descubre la relacion de la victima con el doctor Lambourn, brillante cientifico fallecido recientemente y acerrimo defensor de una nueva ley de farmacia para regular la venta de opio, resulta evidente que no todo es lo que parece.

As commander of the River Police, Monk is accustomed to violent death, but the mutilated female body found on Limehouse Pier one chilly December morning moves him with horror and pity. The victim's name is Zenia Gadney. Her waterfront neighbors can tell him little, only that the same unknown gentleman had visited her once a month for many years. She must be a prostitute, but, described as quiet and kempt, she doesn't appear to be a fallen woman. What sinister secrets could have made poor Zenia worth killing? And why does the government keep interfering in Monk's investigation? Monk, his spirited wife, Hester, and their brilliant barrister friend, Oliver Rathbone, search for answers. Monk's quest to discover the truth behind her death leads him down a shocking path, littered with secrets that have been buried since the infamous Opium Wars. Monk must unravel the victim's link to the widow of a dead doctor, and the doctor's vanished report on the misuse of opium, before the killer strikes again. While the public cries out for blood, From dank waterfront alleys to London's fabulously wealthy West End, the three trail an ice-blooded murderer toward the unbelievable, possibly unprovable truth, and ultimately engage their adversaries in an electric courtroom duel. But unless they can work a miracle, a monumental evil will go unpunished and an innocent person will hang. This is a novel of intrigue and suspense in which Monk is driven to make the hardest decision of his life.