Kiritsugu Tohsaka, son of Rin and Shirou, is transported by his troll of a teacher to Gamindustri. A Great Holy Grail War is about to start, and Kiritsugu's been given the express mission of helping the goddesses win this war. This journey also leads him to realizing a great many things regarding both himself, and his father. Of course, like every other Grail War, simplicity is often the first casualty.