Trouble on the Homefront

You will get this quest after the second round at the Jefferson Memorial. You will get the Vault 101 distress signal, it is a message from Amata asking you to return to Vault 101 to help stop her father. You get back to the Vault to see it in shambles, and divided into two factions, the rebels and the Overseer's people.

The rebels want to leave the Vault, the Overseer wants everyone to stay inside.

 is a Fallout 3 quest. It is also an Xbox 360 and PC achievement.