Exiled from her underground home by Betony, the jealous queen of the piskeys, Ivy sets out to make a new life for herself in the world above - a quest that leads her to mystery, adventure, and a hoard of spriggan treasure. But a deadly poison still lingers in the Delve, and Ivy cannot bear to see her people dying under Betony's rule. With the help of some old friends she sets out to warn the piskeys of their danger, urging them to rise up and free themselves - before it is too late.