A routine rock-hunting expedition in the Pacific Northwest transforms into a high-stakes investigation when two teenagers uncover a criminal operation. The protagonists, two sixteen-year-old boys, find their objective of geological exploration interrupted by the discovery of a gang of log thieves. They must navigate the rugged terrain of Z-Canyon while assisting a new friend and his father, who is physically incapacitated, to secure evidence against the perpetrators. The narrative follows a linear progression, emphasizing the boys' resourcefulness against the physical dangers of the wilderness and the calculated threats posed by the thieves.

Readers frequently highlight the book's focus on the camaraderie between the young protagonists as they navigate the challenges of the wilderness. Discussion often centers on the effective use of the rugged Northwest setting to heighten the tension of the mystery. Critics note that the narrative balances the boys' personal growth with the procedural elements of tracking the log thieves. The story is often cited for its straightforward pacing and clear moral stakes, making it a standard example of mid-century adventure fiction for younger readers.