Keres leads a desperate mission into a nightmare realm to rescue a lost ally—but the horrors waiting beyond the portal are far worse than anyone imagined. Meanwhile, back home, Arcane Acre is overrun by twisted creatures, as the team discovers that the Hollowborn are not merely monsters… they are preparing for war. With reality itself shifting and a terrible new weapon taking shape, the line between heroism and sacrifice is about to be tested--and the Grimm Universe may never be the same.