THERE ARE PLENTY OF WAYS TO DIE in the Grand Canyon.
Forensic geologists Cassie Oldfield and Walter Shaws investigate one way: trouble on the canyon’s Colorado River. Stranded raft. Life vests unused. Rafters missing.
The only clue to the fate of the rafters is a bag of pebbles caught in the bowline. Following that clue, the geologists uncover a hellish scheme. Not only are the rafters in peril, but the river itself is under attack.
The race to stop it takes Cassie and Walter deep into the canyon, and onto the mighty river, putting their own survival at stake.