For fans of Christine Carbo and Scott Graham, an ex-FBI agent is on a desperate hunt for a party of vanished campers while a killer is on the loose.

The rugged landscape of Sequoia National Park is a challenge on the best of days-but when a park ranger discovers an abandoned exclusive campsite with an empty tent and high-end technical gear scattered on the shores of an alpine lake, the wilderness takes on a sinister new hue.

Thirty-two-year-old Felicity Harland-a former FBI agent who left the service in the wake of a personal tragedy and has taken her skills off the grid-is brought in as chief investigator. As a federal agent with the Investigative Services Bureau, she tackles crimes that occur on National Parks lands: unexplained falls, domestic disputes, and now a possible murder case.

The private company that set up the exclusive camp won’t reveal their client list, leaving Felicity with zero clues. As she struggles to find a lead, she’s also haunted by a painful past that dogs her at every step. But when she meets Ferdinand Huxley, a Navy SEAL turned park ranger, she begins to see the value in not just working with a partner, but trusting one, too.

The investigation takes Felicity and Hux deep into a wilderness that tests their physical limits to the extreme-and to the mean streets of Los Angeles, where they begin to learn the grisly truth behind the campers’ disappearance.

Bad things happen in the wilderness-and sometimes they’re not accidents.