Every autumn, John Pentecost returns to the farm where he grew up, to help gather the sheep down from the moors for the winter. Very little changes in the Endlands, but this year, his grandfather --- the Gaffer --- has died and John's new wife, Katherine, is accompanying him for the first time. Each year, the Gaffer would redraw the boundary lines of the village, with pen and paper but also through the remembrance of tales and timeless communal rituals, which keep the sheep safe from the Devil. But as the farmers of the Endlands bury the Gaffer and prepare to gather the sheep, they begin to wonder if they've let the Devil in after all.

When Smith was a boy, he and his family went on an Easter pilgrimage with their local parish to the Loney, a bleak stretch of the English coastline, to visit an ancient shrine, in search of healing for Smith’s disabled brother. But the locals were none too pleased to welcome them, and the two brothers soon became entangled in a troubling morass of dangerous rituals. For years after, Smith carries the burden of what happened that spring. And when he hears that the body of a young child has been found during a storm at the Loney, he’s forced to reckon with his darkest secrets, no matter the cost.