December 1916. Inspector Sam Blackstone is suspicious when he is called to the office of Superintendent Brigham the new head of special branch and confused that Brigham seems to want to see him as little as Sam himself wishes to be there. An already stranger situation grows more strange when Sam discovers what hes there for: a German traitor wants 25000 in exchange for secret intelligence on U boat locations and Max has specifically asked for Blackstone to be the one to deliver the money alone. Blackstone and his sergeant Archie Patterson are certain theres more to it than that but Blackstone cant turn down the job if he doesnt do it some other poor fool will have to. But that is little comfort when as suspected it all goes wrong and Blackstone finds himself on the run from his own colleagues with Patterson languishing in a cell looking at a twenty year stretch if he's lucky.