When the pillar of autumn crashed on alpha halo. chief was stranded on the ring outgunned by the covenant. He moved as quickly as possible away from the troops surging for survivors. luckily he managed to lose them when he dropped in a cave nearby. Suddenly he heard a strange humming noise. As he went deeper into the cave he stumbled upon a gigantic structure Which from what cortana could find this was built long ago but for what reason remains a secret.........