After twelve years of playing his favorite MMORPG game, Momonga logs in for the last time only to find himself transported into its world playing it indefinitely. Throughout his adventures, his avatar ascends to the title of Sorcerer King Ains Ooal Gown. Once prosperous but now on the brink of ruin, The Sacred Kingdom enjoyed years of peace after construction of an enormous wall protecting them from neighboring invasions. But, one day this comes to an end when the Demon Emperor Jaldabaoth arrives with an army of villainous demi-humans. Fearing invasion of their own lands, the neighboring territory of the Slane Theocracy is forced to beg their enemies at the Sorcerer Kingdom for help. Heeding the call, Momonga, now known as the Sorcerer King Ains Ooal Gown, rallies the Sorcerer Kingdom and its undead army to join the fight alongside the Sacred Kingdom and the Slane Theocracy in hopes to defeat the Demon Emperor.

The first recap film of season 1 of the anime TV series Overlord, covering episodes 1 to 7. In the year 2138, the popular online VR game Yggdrasil is quietly shut down one day. However, the player Momonga decides to not log out and is transformed into a powerful skeletal wizard upon shutdown. The game world continues to change, with non-player characters beginning to feel emotions. Confronted with this abnormal situation, Momonga and his loyal followers strive to investigate and take over the new world the game has become.