When their mother is burned at the stake, Syistir and Ada have two options: run or die. For fans of The Ten Thousand Doors of January and Circe, this lyrical tale of magical realism rooted in Nordic folklore is written by a no.1 Sunday Times bestselling author.

Young Systir's world is small and seemingly quiet, but shrouded in secrets. Outside of the cottage where she lives with her beloved mother and adored older sister, lurks the constant danger of being discovered by the villagers for what she truly is: unwanted, dangerous, Huldra. When their mother is accused of being a witch and dragged to the stake, the sisters must run for their lives.

Systir finds herself alone in the Dark Forest that she later comes to know as Trollheim - a magical realm for mythical beings and a sanctuary for those with nowhere left to turn. Here she finds a kindred spirit in the rogue Troll Agagkantor who takes her in and encourages her to live life as her true self, to understand and use the powers she has been hiding away. However, Agagkantor carries secrets of his own and Systir comes to realize that her loyalty might have been misplaced. In the end she has no other choice but to sacrifice everything in order to protect that which matters most - her home.