Hawke: The Law of a Fast Gun by Robert Vaughan

A man haunted and changed by war—whose fingers are equally skilled in the arts of music and death—Mason Hawke has found a new home in Braggadocio, Nebraska. But a dustup in the local saloon has forced his hand, and now two bodies lie lifeless on the dirty floor—a situation an unscrupulous cattleman plans to use to his advantage.

Like Hawke, Clint Jessup is running from his past. But Jessup's sins turned him hard and greedy—and he's willing to drain bone dry a town that's trying to build a future, if it puts an extra dollar in his pocket. The blood of a drifter named Mason Hawke is going to oil his money-making scheme. But it doesn't matter how many killers he sends Hawke's way, because the target plays by his own rules: draw first, shoot fast, and keep watching your back.