The movie continues off where Clementine and Khajiit Dale Badantel ambush the Swords of Darkness. Meanwhile, after registering Hamsuke at the Adventurer's Guild, Momon's group meet Lizzie Bareare who guide them to her house. However, they found the Swords of Darkness, who are turned into zombies. After killing them off, Momon investigates that their new objective is to locate the whereabouts of Nfirea Bareare. Momon tells Lizzie to hire him and rescue her grandson which she agrees. Momon orders Nabe to use the locator scroll to track where Nfirea is held. Momon discovers an undead army at the cemetery and tells Lizzie to warn the people and the Guild of the threat.
At the E-Rantel Cemetery, the undead army assaults the gate to the city. The guards try to defend it but are overwhelmed by their sheer numbers. Momon's group arrive and breakthrough the undead. Momon's group meet the members of Zurrernorn, who are in progress on using the Death Spiral on the city. Momon then leaves Nabe to deal with Khajiit while he and Clementine leave to take their battle elsewhere. Momon tells Clementine that he doesn't need to fight her seriously and their duel begins.
Momon and Nabe begin their respective battles against Khajiit Dale Badantel and Clementine to save Nfirea Bareare. Khajiit summons two Skeletal Dragons that he declares have absolute resistance against 1st to 6th Tier Magic. Nabe hears his master's command to use the power of Nazarick. Now fighting not as Nabe but as Narberal Gamma, she easily obliterates both the dragons and Khajiit with a seventh tier spell.
Meanwhile, Momon continues to give Clementine a handicap and clashes with her repeatedly. Furious at how Momon repeatedly mocks her as a weak warrior, Clementine charges Momon with a full force attack and stabs him in both eyes with elemental strikes. Momon grabs her with a one-armed bear hug. Ainz reveals his true nature as an undead, Ainz torments Clementine that she was defeated by a magic caster that didn't even use his magic against her. Ainz crushes her body with both arms, killing her. Ainz then rescues Nfirea and destroys the Crown of Wisdom. Momon then returns victorious with Nabe, Hamsuke, and Nfirea for resolving the cemetery incident in E-Rantel.
At the inn, Ainz is disappointed with his new promotion with Nabe. He thought they'll be at least be promoted to orichalcum rank. Ainz contacts Albedo, who alerts him that Shalltear Bloodfallen has rebelled against Nazarick.
Shalltear's situation takes place a couple of days from when Ainz achieved his new rank as mythril. In E-Rantel, Sebas Tian and Solution Epsilon pose as members of a noble family from the Baharuth Empire. Their driver Zach attempted to sell them out to Death Spreading Brigade, but are killed by Shalltear Bloodfallen and her Vampire Brides. Shalltear parts from the group to pursue the bandits, where she encounters Brain Unglaus. She easily bests him, humiliating his skills as a warrior causing him to flee. Shalltear then reverts to her True Vampire form and slaughters the entire bandit group. Later she comes across an adventurer team that was dispatched by the Adventurer Guild to dispose of the bandits. Like the bandits the adventurers are killed, however only one survives, Brita, as she used a potion to ward of the vampire. Shalltear though initially fazed by the potion, captures the adventurer and interrogates her. She learns that Brita received a potion from an adventurer named Momon, however, is unable to determine if this was part of her master's plan. When she learns that a lone adventurer was sent back to E-Rantel, Shalltear is distressed as it will expose her. She quickly sends out her vampire wolves to find the human, but all are eliminated by an unknown party.
Shalltear is blocked by their leader, who order one of their number to activate an item. Shalltear senses it to be a mind control item. With her last free will, she throws her final attack that severely injures the wielder before finally succumbing to the item's effect. Later, Albedo reports to Ainz of the situation in the Great Tomb of Nazarick. Before Ainz can take further action Narberal reports from E-Rantel that the Adventurer's Guild has summoned him. Shalltear's presence has been made apparent and the guild is about to launch an attack on her. Momon present at the meeting manages to convince them to allow him to handle the situation, as he has a trump card: a Sealing Crystal. The rest of the adventurers are convinced, save Igvarge who wishes to accompany him. At the destination, Ainz has Igvarge killed stating his death with being a result of the 'battle' with the vampire. Ainz attempts to use his magic ring, Shooting Star to undo the mind control. To his shock, his magic fails and comes to the realization that this is the work of a World Item. He and Albedo return to Nazarick to retrieve the World Items in the Treasury. There he meets with Pandora's Actor who shows Ainz and Albedo to the Mausoleum. Ainz tells her the purpose of the room as a memorial to the Supreme Beings and tells her that should he fall he wants a statue of him to be placed here.
Ainz returns to the site of where Shalltear is situated and begins his attack. The two engage magical attacks and skills. Though Shalltear is considered to be the strongest of the Floor Guardians, Ainz uses various Divine Weapons and Cash Item to combat her. Ainz succeeds in killing her, after which he uses gold to resurrect her. Although Shalltear was resurrected, she is unable to recall all the memories prior to her mind control. Ainz blames himself for this incident yet Albedo reassures him that it is not his fault and that his Floor Guardians will support him. Faced with an unknown adversary in possession of World Items, Ainz orders that the need to strengthen Nazarick has become paramount.
Albedo reports that Aura has discovered lizardmen living in the vicinity of the Great Lake. At the same time, she suggested attacking the lizardmen village in hopes of obtaining their corpses for her master to use as a mean to create stronger undead.
- Platinum Dragon Lord made its first anime appearance in the movie.
- The conversation between Shalltear and Sebas extended than it did in the anime.
- Zaryusu Shasha makes a cameo scene at the end of the movie.
- In contrast to the Anime or Light Novel, this movie seems to have omitted the scene of Ainz calling for the summon of Gargantua and Victim.