The Pony Rider Boys in Montana Or, The Mystery of the Old Custer Trail follows a group of adventurous boys on a thrilling journey through Montana as they explore the old Custer Trail. Arriving in a small town, they learn about local sheep ranching and hear stories of potential dangers in the area, including errant Indians. Eager to begin their exploration, the boys purchase ponies and prepare for the challenges that lie ahead. Their close friendship and enthusiasm drive them forward as they navigate the wilderness, facing natural obstacles and mysterious threats to the ranchers in the region. The story emphasizes the boys' courage and resourcefulness as they uncover secrets tied to the old trail. Along the way, they confront danger and adventure, testing their bravery while deepening their bond. The narrative captures the excitement of the journey, filled with unexpected twists, as the boys grow stronger through their experiences. Their exploration of the untamed Montana landscape becomes a journey of self-discovery and teamwork, facing both the wild terrain and the mysteries that lie hidden within it.