Unlikely heroes, thrilling adventures, clash of cultures, unthinkable choices The underground realm is under attack from mad Overseer Uzza and the Crystal Heart is failing. As things become desperate, Twins Delvina and Retza must brave a treacherous journey to seek help from Zadeki and his people. Will they find the answers they seek before it's too late? What are the twins prepared to do to save their realm and those they love from certain destruction? Blood Crystal is a YA fantasy adventure and the second novella in the Under the Mountain series. It continues Zadeki and the twins, Delvina and Retza's adventures picking up from where Heart of the Mountain left off.