The main quest is a series of quests in The Elder Scrolls Online that serve as the primary focus of the story in the game. If the Vestige owns a chapter such as Online: Morrowind, Summerset, Elsweyr, or Greymoor, then they will not start the main quest by default. To start the main quest normally, the Vestige can travel to their alliance starter city (Daggerfall, Davon's Watch, or Vulkhel Guard) and find a Hooded Figure, who will allow them to start the quest "Soul Shriven in Coldharbour."
In 2E 583, before the events of The Elder Scrolls IV: Oblivion and The Elder Scrolls V: Skyrim, the Vestige is captured and their soul is taken by Mannimarco. The Vestige is imprisoned in Coldharbour, but with the help of Lyris Titanborn, Cadwell and The Prophet, the Vestige escapes.
Meanwhile, the three alliances—the Aldmeri Dominion, the Daggerfall Covenant and the Ebonheart Pact—are locked in combat with each other for Cyrodiil and the Ruby Throne. The Prophet and the Vestige are separated, and the Vestige must find him again to continue the main quest line.
After meeting with The Prophet in the Harborage, he reveals how Molag Bal and Mannimarco were able to weaken the bonds between Tamriel and Oblivion. At an event called the Soulburst, Mannimarco tricked the Emperor into trying to proclaim himself Dragonborn. The Emperor died, and the Amulet of Kings was lost. The Prophet made inquiries about the event, which is why he was thrown in Coldharbour.
While the Vestige is helping Lyris escape Coldharbour, they discover that Abnur Tharn might be a double agent, as he gives Lyris her axe.
- Note: The location of quests outside of Coldharbour, including the location of the Harborage, depends on the Vestige's alliance.
The Vestige learns that the Prophet is actually Varen Aquilarios. Replacing Mannimarco, the Vestige joins Lyris, Varen, Sai Sahan and Abnur Tharn to complete the Five Companions. United, they make their way to Heart's Grief, Molag Bal's fortress. There, they find Mannimarco trapped by Molag Bal, neither alive nor dead. The Vestige can choose to release him or not. Unfortunately, to use the power of the Amulet of the Kings, one of the Five must be sacrificed (either Lyris, Sai or Varen).
Strengthened by the power of Akatosh, the Vestige is able to defeat him and recover their soul. Abnur Tharn flees to Cyrodil with the Amulet, Molag Bal is weakened, and the tear between Nirn and Oblivion is closed.
The Vestige reunites with the remaining Five Companions back in the Harborage.