Princess Thistle has been told her whole life to never let sunlight directly touch her skin. She and her sisters were conceived at a cost-and if they can stay out of the light until the youngest turns sixteen, they might get by without paying for it.

But only one week away from the youngest sister's birthday, Thistle makes a mistake. Her childhood frenemy turned soldier baits her into an argument, and in a fit of defiance, she steps out into a rainstorm-just as the clouds break.

She and her sisters are imprisoned in the enchanted lands under the Blue Mountain. To save her sisters and free herself, Thistle will need to master dream magic to make contact with someone in the outside world.