Battle of the Quarantine Zone

Background info
After The Arbiter has lowered the shield around the Sentinel Wall, he and Rtas 'Vadumee attempt to retrieve the Index, while the Flood are distracted with the Humans and Sentinels. Unknown to the Covenant, Commander Miranda Keyes and Sergeant Johnson also attempt to secure the Index.

Rtas and The Arbiter reach a Gondola and are ambushed by the Flood, Rtas stays behind to keep them at bay. Tarturas gives the Arbiter covering fire in his Phantom, along with a few other Elites.

After the Flood are defeated The Arbiter moves into the Library and attacks Commander Keyes and Johnson, and successfully steals the Index, only to be shoved off by Tarturas into the pit where the Index once floated over.