The Holy Grail War is a ritualistic battle fought to determine who is worthy of commanding the Holy Grail: an omnipotent wish-granting device. The war is held between seven mages, each armed with their own familiar, an ancient heroic spirit of legend.

The Einzberns, a major contender in the grail war, have recruited the infamous mage killer Kiritsugu Emiya as their representative in the Fourth Holy Grail War. Though armed with his own arsenal, Kiritsugu is faced with six other mages vying to win. From bettering humanity to garnering respect, all opponents have their own reasons for seeking the Holy Grail.

Taking place 10 years before the events of Fate/Stay Night, Fate/Zero illustrates the events of the fateful Fourth Holy Grail War.