Seventeen-year-old Annabel Wallis and her family have survived six months of the zombie apocalypse by stealth and cunning. However, Dad has a plan.

Souls deprived of the 'good death' seek out Annabel to fulfill the living's duty to the deceased and help them move on. Eerie, disembodied murmurs haunt the darkest crevices of her subconscious. The voices emanate from a nebulous pool of dark, seething blood. They cry out for attention.

Annabel's mom has a secret, and an antidote, sans one important measurement. Annabel doesn't know it, but her nightmares hold the key to deciphering the medicine's 'wanting measure'. Annabel must complete the remedy if the infected are to have any chance of surviving the horror. To do this, she must stay alive. Worse yet, she discovers that the deceased are experiencing their own apocalypse.

Winter approaches. In the first freeze, the Wallis's will attempt to reach a cold storage facility on their family farm. Weeks pass and the temperatures plummet. Annabel dreams become more urgent and harder to ignore with each passing day. Annabel receives visions from her dead Vietnamese grandmother, who reveals the wanting measure and the destiny Annabel must face. In the confusion of a skirmish, her younger sister is infected. Annabel can save her, if she dares mix the wanting medicine, which has a mysterious 'irreversible price'.