Linda, her friends Kathy and Larry, and her brother Bob are asked to fill in as riding instructors at Saddle Creek Camp in the Sierra Mountains when the camp's regular instructors suddenly leave. But there is trouble at the ranch, and it is up to Linda to find its source and solution. A treasure is hidden in the mountains and someone will stop at nothing to claim it! A terrible car accident and the malicious injuring of horses are just two of the schemes used by the culprit to keep Linda off of his trail. When Chica d'Oro, Linda's prize-winning palomino, is stolen, Linda must search the dark and mysterious mountains to find her before it's too late!