The plot of Fate/hollow ataraxia is based 6 months after the events of Fate/stay night. Like its preceding counterpart, the story is set in Fuyuki City. Bazett Fraga McRemitz, a member of the Mages' Association and a master in the Fifth Holy Grail War, wakes on the fourth day of the Fifth Holy Grail war with a new servant, Avenger, and no memory of what happened to her beforehand. She and Avenger set off to fight and win the Holy Grail War. (wiki)