Everyone knows that workers are using dynamite to blast an eight-mile train tunnel through the Cascade Mountains. But everyone also knows that explosives aren't allowed inside the isolated camp town of Scenic where the workers and their families live. So why did somebody hide a case of dynamite right near the schoolhouse? And why has it disappeared again? That's what ten-year-old Billy and his best friend Finn want to know. Then a sudden explosion rocks the camp, and the boys begin to investigate in earnest. Why is the new man in town, Mr. Renwick, going up to Lookout Rock after dark? And why is his nosy, smart-mouthed daughter, Dannie, watching their every move? The boys' search leads them back to a thirty-year-old gold robbery--and face to face with a dangerous outlaw who will stop at nothing to retrieve his treasure!