London, March 1918. British newspapers carry the disastrous news that the German Spring Offensive has begun, with thousands of British lives lost. Detective Sergeant Joe Keedy eagerly awaits his release from hospital and is anxious to resume the fight against crime on the Home Front.

Against this sombre backdrop, further mayhem strikes in the capital when a fire provides the diversion needed for an audacious bank robbery. The gang of criminals escape with a sizeable haul and leave one police officer dead and another gravely injured in their wake. For Detective Inspector Harvey Marmion, the investigation has a personal connection, but the task of bringing the culprits to justice will prove to be an uphill battle without Keedy, his detective partner, at his side. And nothing in this case is quite what it seems .