Cassie Oldfield and Walter Shaws are forensic geologists who investigate crimes threatening lives and the land—a job that always leads to trouble.

A hotshot venture capitalist—whose gold country is Silicon Valley—hires forensic geologists Cassie Oldfield and Walter Shaws to track his missing brother. The geologists are hooked by the story of this lost man, this wounded soul. And they have the skills to find him. It's what they do: view a rock under the microscope and unravel a mystery. Solve a crime. Prevent a crisis. Find a missing person.

DEATH VALLEY EARNS ITS NAME when a terrorist threatens to unleash lethal radioactive toxins in America's most fragile national park. Forensic geologists Cassie Oldfield and Walter Shaws embark upon a perilous mission to find and stop the terrorist. Mineral clues lead them deep into the desert, and the canyons, pushing them to their limits. The summer heat is brutal. The material they seek is hotter than the desert in August, and they are each vulnerable to its effects.

The volcano beneath her town is seething, and the town's fate now rests in the hands of an emergency planner with a twisted agenda. The mayor's death is personal for investigators Cassie Oldfield and Walter Shaws. This is their hometown. They are desperate to save their families and friends. Their field is forensic geology, and they know how to track mineral clues to find out where the mayor went and what she found.

Cassie Oldfield and Walter Shaws are forensic geologists who investigate crimes threatening lives and the land—a job that always leads to trouble.

A MYSTERY AT SEA plunges forensic geologists Cassie Oldfield and Walter Shaws into deadly waters. When a boat is found deserted off the California coast, it looks to be a simple fishing accident. But there is nothing ordinary going on here. The geologists track the strange incident to an even stranger project. Someone with toxic skills is at work in this sea.

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.

DEEP BENEATH THE STREETS OF SAN FRANCISCO, a murder victim is dumped at an archaeological dig. A note pinned to his shirt warns we will bury you. The question is, who is you? Desperate to learn what happened—and what might happen next—investigators bring in forensic geologists Cassie Oldfield and Walter Shaws. They have a reputation for reading the rocks with an X-ray eye, and unlocking a case.