It's reported that the Holy Sword Excalibur has been discovered inside ALO. Hearing the news, Kirito and Leafa decide to take possession of Excalibur before other players get to it first.

Kirito and the others are tasked with subjugating the Frost King Thrymr, and a quest to recover Excalibur. It's Yui's guess that this isn't a quest planned by the game admins, but something automatically generated by the system. And if that's the case…

Kirito and the others are taking on Thrymr, the Boss lurking at the bottom level of the dungeon. But unable to make much of a dent in Thrymr's HP, they soon find themselves in grave danger. Just then, their new ally, Freyja, raises her voice…