Toni Dwiggins has recently released the fifth book in her Forensic Geology series, River Run. This is an unique forensic thriller series in that the forensic sleuths are geologist. The latest addition takes us into the heart of 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 by the bow line. 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.