Set five years after the Borderlands 2 incident, the handsome Jack, the game's main rival, took over Hyperion, declared himself the dictator of Pandora, and took all the credit for finding the vault-and even claimed responsibility for killing the annihilators. 

Jack also set up a huge H-shaped orbital pedestal in front of Pandora's geostationary moon, blocking most of the light on the planet, creating a Big Brother atmosphere throughout the planet. 

In Border Zone 2, the task of a new group of vault hunters is to kill Jack and restore peace to Pandora. 

Frontier 2 begins when the protagonist gets on a train and goes to an unspecified location to search for the vault. 

The train turned out to be a trap set by handsome Jack to kill all those looking for the vault. 

The vaulting hunters protected themselves long enough to reach a train car full of explosives and a handsome Jack who looked like a dummy. 

The explosion caused the train to crash in the Arctic wilderness, our new team scattered over the wreckage, and when the game began, the vault hunters woke up to find them digging up the remains. 

The mysterious guardian angel then contacts them and explains that handsome Jack must be killed, instructing the player to save the four primitive vault hunters from Hyperion to accomplish this. 

The first four vault hunters all appeared in the sequel as NPC, playing key roles in the main storyline and providing optional tasks to continue their personal stories.