Not every fairy-tale kingdom lies above ground.

Laurel came to the forest hoping a solo retreat might quiet her anxieties, her disappointments, and the nagging sense that life has somehow passed her by. Then she meets Nitch: strange, elegant, irresistible Nitch, who knows the hidden language of mushrooms, walks with a fox at his heels, and promises to show her wonders no ordinary hiker has ever seen.

Beneath the roots of an ancient maple, Laurel enters a glittering subterranean world of glowing fungi, crystal rivers, moonlit balls, and beautiful, inhuman revelers. Nitch calls himself the Mountain King, and in his arms, Laurel begins to wonder whether she has stumbled into a dream—or the fairy tale she has been waiting for.

But the deeper she descends, the more enchantment curdles into danger. For the Mountain King’s kingdom has survived for centuries on secrets, seduction, and sacrifice—and Laurel may be exactly what it needs next.