Despite Sherlock recognizing that Irene is dealing with the Lord of Crime, he sees her off. Irene negotiates with the Lord of Crime in an abandoned church, but before she can turn over the papers, Sherlock arrives, and makes a deal to keep Irene safe.

A series of murders is being carried out by someone claiming to be Jack the Ripper. In response, a vigilante group of the town's poor confronts Scotland Yard while William and the real Jack scramble to uncover the true culprit's aims and foil their plans.