In the Badlands of Montana, young Molly Wilder discovers the fossil remains of a 66-million-year-old winged, flesh-eating monster. This discovery thrusts her into a hidden war between unknown enemies and the truth behind humankind’s own mythology.

In a post-apocalyptic world inhabited by mystical spirits, a human sacrifice ritual goes wrong and a young woman named Seycia must navigate the dangers of the Underworld to protect the family she left behind from beyond the grave.