"As part of the Borderlands series, Borderlands 3 is centered on the planet Pandora, which has been long-rumored to contain Vaults holding vast amounts of treasure and technology, left behind by a mysterious alien civilization known as the Eridians. In decades prior, several corporations have laid siege to Pandora to try to find the Vaults, but the constant conflict and bloodshed has left the planet and its population ravaged and crazed. However, there are still those independently searching for the Vaults, known as Vault Hunters (the player characters).
Borderlands 3 takes place seven years after Handsome Jack's death in Borderlands 2 and the destruction of the Hyperion Helios Station in Tales from the Borderlands. In Borderlands 2, it was discovered that numerous other Vaults exist on other planets in the galaxy. In the power vacuum left by the defeat of Jack, twin siblings Troy and Tyreen Calypso form the Children of the Vault (COV), a violent cult of personality formed from the remnants of the planet's many bandit factions, to gain possession of the other Vaults, specifically one called 'the Great Vault'. Lilith, a member of a race of women with alien powers called 'Sirens', one of the playable Vault Hunters from the first game, and current leader of the Crimson Raiders, a resistance force created to protect Pandora, recruits new Vault Hunters to help stop the Calypsos."
- Borderlands 3 Wikipedia, accessed May 27, 2021