As a Fish and Wildlife police officer, Luke McCain and his partner - a yellow Lab named Jack - spend their days patrolling the rivers, lakes, and forests of the wild and scenic Cascade Mountains in Eastern Washington. After hunters discover human remains inside a bear's stomach, McCain is thrust into the investigation. As more dead women are found in McCain's region, authorities suspect a serial killer is prowling the mountains he knows best. McCain will need his knowledge as an outdoorsman, and his instincts as an investigator, to track the psychopathic predator.

After helping solve the Cascade Killer case, Washington State Fish and 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 two major investigations now closed, Fish and Wildlife Police Officer Luke McCain is called upon for his most high-profile case yet. En route to the Washington State Fair, an exotic cat show’s trailer is stolen. After some of the big cats are released into the Cascade Mountains, McCain and his dog, Jack, try to locate the show’s most menacing member: a Bengal tiger. Meanwhile, there are rumblings that a wild cougar has killed a dirt biker in the region.

Luke's week in the mountains goes from pleasure to business in an instant when he is called upon to help find two teenage boys–one the son of a multi-millionaire Starbucks VIP–who have been abducted at gunpoint during a wilderness survival school expedition. Their captors and the foreigners calling the shots behind the scenes are desperate for their ransom money and willing to do almost anything to get it.

After continuous complaints that a poaching ring is running rampant in Northeastern Washington, Fish and Wildlife police officer Luke McCain is assigned to go undercover to infiltrate the gang. Just as Luke and his fellow officers move to finally catch the poachers red-handed, one of the crooks flees into the mountains and Luke has to hunt him down. Days later, a serial killer suspected of killing dozens of women around the Northwest escapes from custody when a Department of Corrections van crashes in the rugged North Cascades.

When WDFW officials receive an anonymous tip that poachers might be taking young falcons and eagles from nests around eastern Washington and shipping them to a Russian oligarch, Washington State fish and wildlife officer Luke McCain and his colleagues must go to new heights to save the federally protected raptors. Meanwhile, domestic animals are going missing in the region, and Luke investigates the gruesome remains. As details of the animals’ mysterious deaths emerge, rumors explode that a mystical creature—the ever-elusive bigfoot—may be responsible.

When trappers begin encountering illegal bear traps near their traplines, it seems that someone may be purposefully attempting to trap trappers—but why? As one trapper attempts to remove himself from a potentially lethal snare, two major snowstorms start pummeling the Central Cascades. Stranded hunters and a fugitive killer looking for a place to ride out a blizzard have Luke McCain and his yellow Lab, Jack, working overtime to help get everyone safely out of the mountains.

During a routine patrol along the Yakima River, Washington Department of Fish and Wildlife officer Luke McCain encounters a terrified young woman fleeing a man she believes killed two people in a homeless camp in Seattle. Her story convinces Luke to contact his wife, FBI Special Agent Sara McCain, who goes to work with Seattle Police to identify and locate the killer before he finds the woman and makes the potential witness his next victim. Meanwhile, Luke uncovers a group illegally excavating prehistoric mammoth bones on state land.

In Eastern Washington, a group of young ranchers form a secret alliance to hunt the gray wolves that are continually preying on their herds. Using a hidden site on the dark web, they coordinate illegal kills, leaving a trail of poached carcasses and baffled authorities. Miles away, a wealthy environmentalist who helped reintroduce the wolves to the region decades earlier reads about the so-called wolf-killing “Renegades” in The Seattle Times. Furious, he hires hackers and fixers to unmask the people slaughtering “his” wolves.

When seventeen-year-old Emma Thomas uploads a new song to Spotify and it explodes into a viral sensation, she becomes an overnight enigma the nation can’t stop talking about. But Emma is nowhere to be found—she’s thousands of miles from home, hiking the rugged Pacific Crest Trail with family and friends, chasing solitude and inspiration. Unbeknownst to her, a lovesick admirer has followed her across the country, determined to find her on the trail. Unprepared and out of his depth, he disappears into the vast wilderness.