An extinct disease re-emerges from the melting Alaskan permafrost to cause madness in its victims. For recent apocalyptic cult escapee Wynter Roth, it’s the end she’d always been told was coming. When Wynter Roth is turned out of New Earth, a self-contained doomsday cult on the American prairie, she emerges into a world poised on the brink of madness as a mysterious outbreak of rapid early onset dementia spreads across the nation. As Wynter struggles to start over in a world she’s been taught to regard as evil, she finds herself face-to-face with the apocalypse she’s feared all her life—until the night her sister shows up at her doorstep with a set of medical samples. That night, Wynter learns there’s something far more sinister at play and that these samples are key to understanding the disease. Now, as the power grid fails and the nation descends into chaos, Wynter must find a way to get the samples to a lab in Colorado. Uncertain who to trust, she takes up with former military man Chase Miller, who has his own reasons for wanting to get close to the samples in her possession, and to Wynter herself.

In this sequel to The Line Between, cult escapee Wynter Roth and ex-soldier Chase Miller emerge from their bunker to find a country ravaged by disease, and Wynter is the only one who can save it. Six months after vanishing into an underground silo with sixty others, Wynter and Chase emerge to find the area abandoned. There is no sign of Noah and the rest of the group that was supposed to greet them when they emerged—the same people Wynter was counting on to help her locate the IV antibiotics her gravely ill friend, Julie, needs in order to live. As the clock ticks down on Julie’s life, Wynter and Chase embark on a desperate search for medicine and answers. But what they find is not a nation on the cusp of recovery thanks to the promising new vaccine Wynter herself had a hand in creating, but one decimated by disease. What happened while they were underground? With food and water in limited supply and their own survival in question, Chase and Wynter must venture further and further from the silo. Aided by an enigmatic mute named Otto, they come face-to-face with a society radically changed by global pandemic, where communities scrabble to survive under rogue leaders and cities are war zones. As hope fades by the hour and Wynter learns the terrible truth of the last six months, she is called upon once again to help save the nation she no longer recognizes—a place so dark she’s no longer sure it can even survive.