After fierce war chief Ulzana and a small war party jump the reservation bent on murder and terror, an inexperienced young lieutenant is assigned to track him down.

After his best friend and war buddy is mysteriously gunned down, Mike Hammer will stop at nothing to settle the score for the man who sacrificed a limb to save his own life during combat. Along the way, Hammer rides a fine line between gumshoe and a one-man jury, staying two-steps ahead of the law—and trying not to get bumped off in the process.

Clearly influenced by the darker, more sinister style of spaghetti westerns, Dirty Little Billy offers a unique insight into the beginnings of the notorious outlaw Billy The Kid.