Crossfire — George G. Gilman

A dead man is slung over Steele's saddle as he rides into the town of Black Rock. The townsfolk burn with rage, for the murdered man was well-loved; taken hostage during a bank raid, he had been slain by the notorious Tyler gang.
Inspired not by sentiment but the sweet smell of a $5000 reward, Steele proffers his shooting irons to aid the posse's pursuit of the vicious gangsters.
But the posse is swamped by a hail of lead in the deadly cross-fire of an ambush. Who set them up? Steele is suspect Number One, and the stricken sheriff's son swears vengeance. The town turns against Steele, and he turns to the Tyler's for dollars and deliverance.
In a devastating denouement of double-cross and death, Steele saves his hide, but look set to hang ... a problem that leaves him in suspense.