London, 1870: The body of a Hungarian immigrant is found dead in what appears to be a ritualistic killing, with a bayonet through his heart, his fingers broken and his body surrounded by seventeen blood-dipped candles. At first, Commander William Monk of the Thames River Police suspects the killer is from within the community, but when another murder takes place, Monk fears the immigrants are being targeted by an outsider... Meanwhile, Hester is reunited with a doctor who had been left for dead on a Crimean battlefield. Traumatised by his experiences, Fitz has made his way home via Hungary and is now living in the community. Hester is determined to help him and, when he is accused of the killings, she sets out to prove his innocence...