"The Frontier Boys in the Sierras: The Lost Mine" is an adventure novel written by Wyn Roosevelt. This story follows the Frontier Boys, a group of young adventurers, as they journey into the rugged and remote Sierra Nevada mountains in search of a lost gold mine. The plot centers around the discovery of an old journal that hints at the location of a hidden gold mine deep within the Sierras. Intrigued by the prospect of finding the lost treasure, the Frontier Boys set out on a challenging expedition filled with dangers and obstacles. Along their journey, they encounter harsh wilderness conditions, wild animals, and other treasure hunters who are also eager to claim the gold. As they venture further into the Sierras, the Frontier Boys must rely on their wits, survival skills, and teamwork to navigate the treacherous terrain and outsmart their rivals. The story is a thrilling blend of adventure, mystery, and exploration, highlighting the importance of determination, resilience, and cooperation in the face of adversity. "The Frontier Boys in the Sierras: The Lost Mine" is an exciting tale that captures the excitement of the great outdoors and the thrill of uncovering hidden treasures. It offers young readers an adventurous and suspenseful story while emphasizing values such as bravery and camaraderie.