A YOUNG MAN DISAPPEARS in the California gold country. He leaves behind a gold-flecked rock and a vial of toxic mercury. He is a misfit in the modern world, a throwback to Gold Rush days.

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.

Joined by their edgy client, Cassie and Walter track the mineral clues deep into the wilderness. Their journey soon turns harrowing, plunging into the dark history of the legendary lands, into the dark past of the brothers, into a poisonous sibling feud that threatens both lives and the land.

And they are not the only ones on the hunt.

—All books in the series are complete novels and can be enjoyed in any order.

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 geologists soon learn that they are up against more than human malice. The unstable atom—in the hands of an unstable man—is governed by Murphy's Law. Whatever can go wrong, will go wrong.

And it does.

—All books in the series are complete novels and can be enjoyed in any order.

NO WAY OUT—so says the note in the pocket of the murdered mayor.

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.

As the volcano moves toward red alert, Cassie and Walter race to prevent 'no way out' from becoming a prophecy. All books in the series are standalone novels and can be enjoyed in any order.

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.

Cassie and Walter are forensic pros--but they are up against a master in an undersea world where they don't belong. They must face their deepest fears in order to end this project.

If they fail, lethal creations will be unleashed.

Unstoppable.

All books in the series are standalone novels and can be enjoyed in any order.

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.

All books in the series are standalone novels and can be enjoyed in any order.

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.

The key to this case is finding out where the victim took his final steps. Tracking mud from his boots, the geologists follow the mineral trail to a startling site at the city's wild edge.

As they rush to learn the connection between this unlikely place and the dig on the other side of the city, they unearth the meaning of we will bury you.

Word by alarming word.