A teenage girl in the Midwest becomes infected by an outbreak of a disease that slowly turns the infected into cannibalistic zombies. During her transformation, her loving father stays by her side.

Of all the things of old and gray, there’s none so craved as better days. Those are the words crestfallen Mike clung to after falling into a crevice high up on that Colorado mountain. He held tight to those words—his father’s words—as an ancient being crept out of the darkness and into his memories to rake across his history. Three years later, clinically depressed Carter Pope wakes in the wreckage of his RV after it had swerved to miss a police cruiser in the middle of the snow-ridden road. When he learns that his best friend—his emotional anchor—is missing, he goes out in search but instead finds the enigmatic Roy Roland, an ex-sheriff who sacrificed fatherhood to indulge his acute grief. Together, the two make their way into the sleepy mountain town of Broomfield, Colorado, where they discover the townsfolk have gone missing, all except a few stragglers, including Hannah Poverly, who begins to realize that she may be sharing her mind with another entity. A dreadful truth becomes apparent in their search for answers: the mass exodus may have something to do with their beloved church pastor, Pastor Mike. And it may be spreading. The path to survival leads them across horrifying, primordial abominations desperate to offer bliss in exchange for blood and directly to Saint Curat, an arcane entity with roots that slither back through history. Carter, Roy, and Hannah are thrust into a centuries-spanning mystery that threatens to unravel not only their sanity but humanity itself.