Fascinated by his father's profession, Nathan wants to follow in his footsteps and become an assassin.  When he receives an unexpected call giving an opportunity too good to refuse, unheeding his father’s warnings, Nathan joins Occidendum, a company of assassins. Confronted by the harsh realities of his chosen profession, Nathan realises just how woefully under-powered he is. With his and the lives of the people around him on the line, he has to use his extraordinary brain to even out the field and survive in a world of legalised assassinations.