River issues a twenty-four hour evacuation notice for Athens, but Emmett Brown is twelve hours away at the Long Lake Camp when the text comes in.

While preparing for the long ride home, Emmett is interrupted by the arrival of his old mentor, One—a New Texas Knight and former Navy SEAL. But with the Knights implicated in River's disappearance, Emmett has to determine whether One is an old friend or a new enemy.

In New Texas, River's MIA status threatens international stability, leading Secretary of State Aidan Stone to join the military unit dispatched to the old McChord AFB in Tacoma, WA. While there, he reveals a shocking discovery: River Kingston might actually be Eryn Stone, Aidan's younger sister, who went missing after the Camp Winslow massacre five years ago.

Unfortunately, River's village isn't the only settlement remaining in the Seattle-Tacoma area; Whidbey Island is still around, and they don't take kindly to trespassers.

The heart-stopping finale in the Stone World Saga is here. It's perfect for fans of World War Z, Fallout, and Mockingjay.