Sisters Sommer and Winter are shaken and bewildered in the wake of a goblin horde smashing apart their family's vacation cabin and absconding into the night with their parents. But the mysterious, jagged, hulking sword they stumbled on as they fled into the forest offers the young girls surprising strength, agility, and a vicious means to fight back. When they seek shelter with an old couple in the woods, they learn the truth behind the monsters, the fairies, the withering realm known as the Autumn Kingdom, and the deadly sacrifice it requires...