The plot revolves around a Grail War that is a flawed copy of the Third Holy Grail War in Fuyuki. Following the conclusion of the third Grail War, an organization from the United States, whose members are magi distinct from the London-based Mage Association, obtained data from Fuyuki's Grail War and devised their own ritual. Seventy years later, they designated the city of Snowfield as the Sacred Land for their own Grail War. They failed to successfully replicate every aspect of the ritual, resulting in an imitation that lacks the Saber class and permits the summoning of strange Servants because the definition of a "hero" has become blurred.