One night, years after Kiritsugu's death, Shirou is cleaning at school, when he finds himself caught in the middle of a deadly encounter between two superhumans known as Servants. During his attempt to escape, the boy is caught by one of the Servants and receives a life-threatening injury. Miraculously, he survives, but the same Servant returns to finish what he started. In desperation, Shirou summons a Servant of his own, a knight named Saber. The two must now participate in the Fifth Holy Grail War, a battle royale of seven Servants and the mages who summoned them, with the grand prize being none other than the omnipotent Holy Grail itself.