Fourteen Heroic Spirits gather for an apocryphal Holy Grail War in the city of Fuyuki, where seven magi and their Heroic Spirits once clashed. Amid the chaos of the Second World War, a magus makes off with the Grail. Decades later, the Yggdmillennia clan -- holder of the rail -- secedes from the Mage's Association and declares independence. The Association, angered by the move, sends assassins after the clan. When the assassins are wiped out by a Yggdmillennia Servant, the Holy Grail War reaches an unprecedented scale -- a Great Holy Grail War.