Your undercover operation is blown before you get to San Francisco. What next? If you're Orpen, you join the cops. Sort of. 

It's the Fall of 1883. Irish revolutionaries are changing the face of London with American dynamite, and not in a good way. Irish-born London Metropolitan Police Sergeant, Robert Emmet Orpen is sent, badly disguised as a tourist, to San Francisco to prevent at least some of the explosives getting into the wrong hands. He realizes that he may be out of his depth when his cover is blown before he even gets as far as the west coast. Now what does he do? First, he charms his way onto the San Francisco police force, where he is assigned to the coattails of a cynical, 'larger than life' Civil War veteran (from the losing side). Then he finds himself caught up in a murder involving one of the two violent Irish factions vying for supremacy in one of the most Irish of American cities. Orpen is going to wish he never heard of the murderous Knights of the Red Branch.