Vultures' Sanctuary by Robert E. Howard

When a desperate outlaw kidnaps a farmer's daughter to buy his way into a notorious bandit gang, Texas cowboy Big Mac takes it upon himself to track them into the foreboding Guadalupe Mountains. Braving the vulture-haunted lair of the ruthless outlaws alone, can Mac use his wits and grit to overcome nearly impossible odds and rescue the girl from the clutches of the murderous gang leader, his longtime enemy?