and take a strategic bluff from the Covenant to use as a base of operations. Captain Keyes is captured by the Covenant, and taken aboard the Covenant cruiser Truth and Reconciliation; the Master Chief and a squad of Marines board the Truth and Reconciliation, rescuing the captain. Keyes has learned that the ringworld they are on has vast significance to the Covenant- they believe that "Halo", as they call the ring, is a weapon of unimaginable power. Escaping from the Covenant cruiser, Keyes gives the Master Chief the mission of finding the Control Room of Halo before the Covenant. The Master Chief and Cortana discover the location of the Control Room, and with the help of some Marines, insert Cortana into Halo's computer network. However, Cortana realizes that the ring is not a weapon as they understood at all- but before the Chief can press her with questions, Cortana tells the Master Chief to find Captain Keyes. Dropped into the swamp where Keyes and his squad disappeared, the Master Chief discovers that the Captain has been captured and both human and Covenant soldiers have been turned into zombie-like creatures by bulbous aliens. One soldier, Private Wallace Jenkins, is left still semi-conscious and painfully aware of his predicament, unable to control his movement or actions as his former friends and he attack McKay's troops. Jenkins intends on ending his life, but is instead captured by McKay for study. The Chief is approached by Halo's resident A.I., 343 Guilty Spark, who informs the Chief that the creatures he has encountered are called the Flood, a virulent parasite that infects hosts and converts them into either forms for combat, or for reproduction. To activate Halo's defenses, Guilty Spark needs the Master Chief's help. In Halo's Control Room, Guilty Spark gives the Master Chief the key to activate Halo, but is stopped by a furious Cortana. Cortana explains that Halo is a weapon, but it doesn't kill the Flood- it kills their food, meaning humans, Covenant, and any other sentient life. Realizing that they have to stop Guilty Spark from activating Halo, Cortana and the Master Chief decide to destroy Halo by detonating the crash-landed Pillar of Autumns fusion reactors. In order to do this, they need Captain Keyes' neural implants. Cortana discovers the Captain is still alive, held prisoner once again aboard the Truth and Reconciliation, now in the hands of the Flood