All his life, Fionn has been certain of one thing: there is always a way to win a battle. After the Band of the Greywolf defeated the Golden King, Fionn decides it is finally time for him to retire. But when their triumph unleashes a mythic cycle of gods and destruction, the Band of the Greywolf discovers they are in the middle of the Apocalypse. Exhausted, low on resources and allies, Fionn and the others must muster any sliver of hope if they are to save Theia one last time. As the final battle looms, Fionn and Gaby face a stark choice, while Alex, Sam, and Kasumi must step up to lead the Band of the Greywolf. One last journey to save the Roots of Hope. In a world where magic and science intermingle, anything is possible, including saving the universe.