John Carshalton, late of the British army, returns to the town of Arabella in Kansas to take up a new job as town sheriff. He quickly earns the respect of the townspeople and enjoys a peaceful life until he gets word of outlaw gangs terrorizing towns along the Kansas-Missouri border. US army intelligence suggests that these are no ordinary gangs, but part of a larger more sinister force, and when John is asked by an army officer to pose as a deserter from the British Army in Canada and try to infiltrate whatever kind of force is being raised he agrees, believing this to be a simple fact-finding mission. However, John soon finds him caught up in a web of violence and intrigue that threatens to destroy him and all he holds dear.