As the west rapidly becomes civilized, a pair of outlaws in 1890s Wyoming find themselves pursued by a posse and decide to flee to South America in hopes of evading the law.

When circumstances force an outlaw to impersonate a county governor and clean up a corrupt town, the Robin Hood figure finds himself in a showdown with the local godfather.

In 2071, roughly fifty years after an accident with a hyperspace gateway made the Earth almost uninhabitable, humanity has colonized most of the rocky planets and moons of the Solar System. Amid a rising crime rate, the Inter Solar System Police (ISSP) set up a legalized contract system, in which registered bounty hunters, also referred to as "Cowboys", chase criminals and bring them in alive in return for a reward.