The sixth thrilling mystery in the New York Times bestselling series
U.S. park ranger Anna Pigeon is enjoying the open spaces of Colorado when she receives an urgent call. Her friend and fellow ranger has been seriously injured while exploring a cave in New Mexico's Carlsbad Cavern Park, and she specifically asked Anna to join the rescue team. Anna must battle her claustrophobia and join the mission, and soon she finds herself facing her fears—and a potential murderer.
