Condor Mountain — Angela Dorsey

Elena's dad is trapped with his horse in the Andes mountains. Above them, the condors are circling, ready to strike as soon as they consider their prey weak enough. Elena is the only one who can get to her father and his horse in time, but she doesn't believe they're in danger - and she certainly doesn't trust the strange girl who says she'll help, the girl who rides the wild mare that no one has ever been able to tame.