Set in the rugged hills of 19th-century Wales, the story revolves around a young girl named Gwen who struggles to hold her family together amidst a series of inexplicable events. She lives with her frail mother and younger sister on their isolated farm, which has faced several hardships. Their life begins to unravel further with the unexplained illness of their livestock and a foreboding sense of an evil presence that seems to creep ever closer, casting shadows on their dwindling safety and stability. Local villagers grow increasingly suspicious and hostile, as suspicion and superstition run high in the tight-knit rural community.

As these ominous occurrences escalate, Gwen's mother behaves more erratically and becomes progressively weaker. Gwen is thrust into the position of the family's primary caretaker while faced with mounting pressures from their neighbors and an unexplained malevolence. Mysterious tensions rise as she fights to maintain normalcy and protect her home from forces beyond her understanding, with every day bringing new challenges and dangers. Just as hope seems to dwindle, Gwen learns harrowing truths about her family's plight and must find an inner strength she never knew she possessed to face the darkness threatening to engulf them all.