When adventure craving Zelda Braun receives a letter calling her to Theria's aid, she soon realizes to be careful what you wish for. Especially after Theria is approached by a trio of Animali and sent on a dangerous mission: to infiltrate the Underneath, the realm between realms, and stop the escape of ancient monsters known as Shadows. If left to roam, the Shadows will feed on the souls of mankind. But Theria can't do it alone. They are joined along the way by a cursed shapeshifter looking for redemption and a young desert thief, but can they reach the Underneath before the Shadows find them? Or will they be overcome by the shadows within themselves?