In the latest in this USA Today bestselling series, Nevada sheriff Porter Beck receives an anonymous riddle leading him to a body hidden for decades, leading Beck and his team in a chase to unravel riddles that will help them uncover and stop a long-time serial killer.

Porter Beck is the sheriff of Lincoln County, Nevada, a vast expanse of desert and mountains best known to the outside world for the top-secret installation called Area 51. Just down the highway sits a weathered mailbox where UFO believers leave messages for aliens. But this time, the message is for Beck.

It’s a riddle. And when Beck and his team decipher it, the answer leads them to the shrinking waters of Lake Mead and an oil drum chained to the bottom. Inside are the remains of someone missing for more than fifty years, someone tied to Beck by a thread of DNA stretching deep into his own past.

Enter Jett Lowell, a pint-sized but fearless FBI profiler who believes Beck’s riddle is connected to one she received seventeen years earlier, shortly before the disappearance of someone close to her.

Convinced they are hunting a serial killer, Beck and Jett follow a trail of riddles from the deserts of Nevada to the mountains of Arizona, and finally to the red rock wilderness of Utah, racing to uncover a chain of murders spanning generations before the killer unleashes a final, horrendous act decades in the making.

"A superior mystery that manages to be both cerebral and action-packed."—Kirkus Reviews