To Kill the Valko Kid — Michael D. George

Retired marshal Clem Everett rides into Sioux City moments after the infamous Johnny Sunset arrives. It's not long before Clem discovers that Sunset is there to claim the reward money on the lawman's old pal Valko. From an arrangement made way back, Clem knows Valko is due to appear in the city the next day. The clock is ticking towards midnight, and there is no way to warn his friend that the deadliest bounty hunter in the West is intent on gunning him down...