Rin, Archer, Shirô and Saber run into a girl named Illyasviel von Einzbern and her seemingly unstoppable Servant, Berserker, in a long-ranging battle that could destroy the four of them.
Rin finally asks Shirô out on a date, but their enjoyment is cut short when Caster makes her move. Shirô is forced to make a difficult decision to protect the people he cares about.
Rin suspects Kuzuki might be the Master of Caster. With the help of a hesitant Shirô, she implements a dangerous plan in a remote location to test out her theory.
Despite losing Saber, Shirô is determined to fight. Since Caster is protected by Kuzuki and Archer, Shirô and Rin decide to team up with another Master. Left with no other option, they set out to find Illyasviel and Berserker.