When Ray O’Brien volunteers to raft the Grand Canyon with a research team, the last thing he expects is murder. After a few days on a river closed to the public, one of the volunteers is found struck dead on a secluded beach. Sixty wilderness miles from contact with other people, the group must carry on in total isolation, sure someone committed murder and may kill again.

Despite the terrible timing, Ray falls for Duke, the group’s handsome ranger, who seems to return the attraction. Ray and Duke join forces with Jenny Bridger, the group leader, to solve the mystery. Jenny must act with confidence and decisiveness but meets puzzling resistance from the volunteers. Ensuring safe passage for all will mean overcoming the group’s misgivings and slaying Jenny’s own demons, but her compassion for the victim’s widow may lead them all astray.

The age-old Canyon becomes more and more ominous as the group fights to survive alone in nature and uncover a murderer among them.