After helping solve the Cascade Killer case, Washington State Fish & Wildlife officer Luke McCain thinks life will return to normal: hunting with his Labrador named Jack, policing Eastern Washington's wilderness, and spending time with his girlfriend, FBI agent Sara Sinclair. But when dead bodies are discovered in illegal marijuana fields hidden in the Cascade Mountains, McCain and Jack are thrust into a new investigation.

With the help of Agent Sinclair, county law enforcement, concerned citizens, and, of course, Jack, McCain works to discover who is killing workers within the region's drug trade. As illegal marijuana fields continue to appear, and bodies pile up, McCain and the others must run down every lead in the hopes of catching their shooter before the killer exacts more vengeance.