The year is 1894. Europe has been suffering from a series of Anarchist terror attacks, the latest of which was the bombing of a Parisian textile mill which killed twelve people. The perpetrators of this act - the seven Hirsch Brothers - are believed to be on the run in London. Billings, Flynt and Clarkson are called in by Special Branch to help locate them. But the investigation goes spectacularly wrong. One by one, the Hirsch Brothers are found dead and the police have no idea who is killing them.