In 1883, the London Metropolitan Police formed the Irish Bureau. Its twelve detectives attempted to counter Fenian violence. In the following decades, the unit became Special Branch, tasked with all covert policing operations. The official story ends there.

The accounts of Detective Sergeant Sidney Wainwright illuminate another history, a secret history. One that is still denied to this day. While working under the imperious Inspector Tarrant, Sidney discovers a hidden world of paranormal threats to society. Yet his greatest challenge proves to be his mysterious commanding officer.