After the deadliest battle in the history of the Underground, Autumn and Luke Oaken find themselves in the roles of co-rulers, catapulting them into adulthood and forcing them to grow up. Even after the death of the Atrum and Shadows' evil leader, attacks are only becoming more frequent, the death toll steadily rising across the Underground. The remaining Vaun sibling’s mind is pre-occupied by none other than the new queen of Arbor Autumn Oaken. After a tragically fatal attack on her beloved town, he pays her a visit and offers her a life-changing bargain she isn’t certain she can turn down. After all, she’s spent her whole life valuing the happiness and safety of others above her own…why stop now? Experience the thrilling finale of The Underground Series in book Alder.