Naofumi Iwatani travels to Siltvelt, a demi-human nation that worships the Shield Hero, after assassins from Q'ten Lo target Raphtalia over a case of mistaken identity. Siltvelt's populace welcomes him, but factions inside the country have their own designs on the Shield Hero's presence. The Phoenix, one of the Four Guardian Beasts, is due to return, and no one of the Four Heroes can prepare for it alone. This fourth TV season adapts volumes 13-14 of the light novel.