Systir's world is small and quiet, but shrouded in secrets. Outside of her family's cottage lurks the constant threat of being discovered for what she truly is: unwanted, dangerous, Huldra. When their mother is accused of witchcraft and dragged to the stake, she and her sister must run for their lives. Yet only Systir escapes. Taken in by the rogue troll Agagkantor, Systir finds herself in the Dark Forest, otherwise known as Trollheim. Here, she discovers a magical realm for mythical beings and a sanctuary for those with nowhere left to turn. For Systir, it's a chance to forge a new family and live life as her true self. But questions remain about her missing sister, and Agagkantor carries a secret of his own - one that could unravel Systir's past and destroy the Dark Forest entirely...