Teagan leaves her flesh and bones behind to join Finn in hunting the uncanny creatures that have spilled from Mag Mell into Chicago, realizing that she must destroy the Dark Man and his minions once and for all to save her remaining loved ones.
Soon after the mysterious and alluring Finn arrives at her family's home, sixteen-year-old Teagan Wylltson and her disabled brother are drawn into the battle Finn's family has fought since the thirteenth century, when Fionn MacCumhaill angered the goblin king.
The very clever Oona saves her husband, the giant Finn McCool, by outwitting Cuhullin, who seeks to prove that he is the strongest giant in the world by beating Finn.