The Burning Hills by Louis L'Amour

Wounded, dehydrated, and escaping a violent feud with the men of Bob Sutton's ranch, trace Jordan is near collapse when he descends from the heat of the desert into a cool, secluded Canyon. He wakes to find a beautiful woman gently nursing him back to health. Strong and proud, Maria Christina has also suffered at the hands of Sutton and his men. The experience has left her hostile and defiant. Trace, intrigued by Maria's grit and determination, can't help trying to peel back her layers-but his attraction makes her a target. Sutton's men are watching and waiting for trace to show himself. If he escapes, Maria will have to face them alone. But if he convinces her to go with him, trace and Maria will have to survive a heat-blasted, waterless desert. And if that doesn't kill them, the apaches will.