Seven Days To Die — J.A. Johnstone

Once he was a young, happily married businessman. Then he lost his wife to human madness and that young man was gone, replaced by the Loner, the wandering son of legendary gunfighter Frank Morgan and the current occupant of a cell in Hell Gate prison. The Loner's crime? He looked too much like an outlaw who escaped from this very prison. So the Kid teams up with a fellow inmate with an escape plan, vowing to hunt down a look-alike killer on the loose. But in or out of prison, Frank Morgan's boy knows better than to trust anyone. And with Hell Gate behind him, any day could be his last. So every bullet must be his best.