As the Battle on Installation 04 rages on between the Covenant and UNSC forces, an evil so terrible lies silently in slumber. In the pursuit of knowledge and power, the Covenant unleash a force that even they fear. As Containment Facilities across Alpha Halo are breached, one in particular is at the forefront of this. On a lone island in the middle of Installation 04's many seas, a facility unlike the others contains something that will make the Flood thousands of times more formidable to combat. A Gravemind lies dormant deep inside the recesses of this vault. The Battle for Installation 04 is about to reach its pinnacle.