The Doctor, Amy and Rory find themselves in the American wild west
sometime in the 19th century. The small town has a Marshal but they're
not that keen on the new arrivals. They are also under threat from an
alien, a half-man half-robot hunter who is out to eliminate the Doctor.
Not the we know but another, Kahler Jex, who has escaped from his world.
He's done many good things for the local community but his past is
somewhat questionable. When the Marshall is killed, it's left to the
Doctor to decide how best to proceed.
