One night in the Greenwich Royal Naval Hospital nurse Hester Monk is approached by a terrified girl. She's from a hidden ward of children all subject to frequent blood-letting and her brother is dying. While William Monk's River Police fight to keep London safe from gun-runners Hester takes on a new role at the hospital helping to administer a secretive new treatment. But she slowly realises that this experimental cure is putting the children's lives at risk. Attempting to protect them she comes under threat from a rich powerful and very ill man who is desperate to survive...

Part of the The William Monk Series series.