Halo 2 Storyline

Plot

The Brute Chieftain Tartarus about to brand Thel 'Vadamee, who was once a Supreme Commander, with the Mark of Shame.

It begins with the trial and punishment of the former Supreme Commander of the Fleet of Particular Justice, Commander Thel 'Vadamee, who later becomes the future Arbiter who is branded with the Mark of Shame by Tartarus due to his failure to protect the Sacred Ring during the events of Halo: Combat Evolved.

The story then turns to Earth's Orbital Defense Platform Cairo Station, where SPARTAN-117 receives the new MJOLNIR Mark VI armor from the Master Gunnery Sergeant. He then meets Admiral Terrence Hood for an award ceremony held for the dual purposes of awarding meritorious acts and boosting the morale of the surviving human population and noted as a war hero (John-117 has already received all medals except for the "Prisoner of War" medal). The festivities are soon interrupted by Cortana reporting "15 Covenant Capital Ships holding position just outside the kill zone", signaling the start to the Covenant Siege of Earth. UNSC Marine forces along with SPARTAN-117 protect the station from the invading Covenant Naval infantry but other stations were destroyed by the Covenant. After sending the bomb that the Covenant had placed on the ship back into space (destroying several ships) he landed on a UNSC ship and then they head to the surface of Earth to New Mombasa to fight off the Covenant Army, led by the High Prophet of Regret. After the Covenant invasion force is halted by the UNSC defenses, the Prophet of Regret flees Earth with Keyes and her detachment in pursuit on the In Amber Clad. The hasty in-atmosphere jump destroys most of the city of New Mombasa.

The story then turns back to the disgraced Sangheili Commander, Thel 'Vadamee, who is given the chance of redemption by taking up the mantle of Arbiter, along with the imminent mortality of the task. The new Arbiter accepts and becomes the will of the Prophets, seeking to complete the impossible task assigned for redemption from his crimes. Thel 'Vadamee is tasked with the assassination of a Heretic Leader, whom is disillusioned with the Covenant following the events of Installation 04 up to its destruction. Thel 'Vadamee tracks the Heretic Leader throughout the gas mine (battling the Heretics and the Flood) where the Heretics sought refuge. When Thel 'Vadamee is finally able to face the Heretic Leader, 'Refumee asserts his belief that the Prophets have lied about the Great Journey, punctuating this with the entry of a Monitor. Before Thel 'Vadamee could learn more of the claims, the battle resumes, and the Heretic Leader is killed before any meaningful discourse taking place. Tartarus appears to extract him and Guilty Spark, preventing Thel 'Vadamee from learning any information from Spark. He leaves not knowing what caused the Heretics to betray their sacred oaths to the Covenant.

Turning back to the SPARTAN-117's story, Keyes exits slipspace in her ship undetected with the Prophet of Regret unaware that he had been followed. To the surprise of the pursuers, they discover that Regret led them to another Halo Ring. Keyes soon determines that their objective is to Capture the Prophet of Regret and stop the Covenant from firing the Halo Rings, SPARTAN-117 is dropped onto the surface of Installation 05 with ODSTs to remove Regret. In the course of pursuing Regret, SPARTAN-117 discovers with the aid of Cortana that the Prophet intends to personally activate Halo. Keyes decides that the new revelation about Regret's intentions warrants his death, which SPARTAN-117 successfully achieves. But before being able to make his escape, the Covenant and high charity which has just arrived attempt to kill SPARTAN-117 by glassing the area, and he jumps into the lake surrounding Regret's location. Incapacitated from the shock of the Covenant bombardment, SPARTAN-117 is last seen being dragged into the depths of the lake by the tentacles of the Gravemind.

The story now shifts back to Thel 'Vadamee on the High Charity, in orbit around the ring. The Hierarchs had declared Regret's death to be the Elites' failure, and they were removed as the protectors of the the Prophets, who bestow the role to the Brutes, causing more tension between the Brutes and Elites who are already at odds with each other. Despite this Thel 'Vadamee is given a new mission to recover a Sacred Icon from the Library, having not died in his previous mission as all had expected. Making his way through the Quarantine Zone facing scores of flood and sentinels on the surface of Installation 05 seeking the Activation Index, Thel 'Vadamee makes his way into the Library and captures the Index along with Keyes and Johnson after they recovered it from its protective housing. Before he can take possession of the Index, Tartarus again intervenes in Thel 'Vadamee's task. After taking the Index into his own personal possession, Tartarus then reveals that the Hierarchs intended for his death to oust the Elites. His treachery revealed, Tartarus knocks Thel 'Vadamee unconscious down a shaft in the Index chamber to the abyss below.

Beneath the Library, SPARTAN-117 finds himself in the clutches of the Gravemind, the creature that acts as the sentient intelligence of the Flood. Although Thel 'Vadamee had fallen from a great height, he is saved from plunging to his death by the Gravemind's tentacles. It is within the Gravemind's chamber where Thel 'Vadamee and SPARTAN-117 meet. In addition, the Prophet of Regret is infected and assimilated into its mass. Also introduced is 2401 Penitent Tangent, Monitor of Installation 05. Both characters act as exposition to Thel 'Vadamee, as Regret remains steadfast to his faith, and the Monitor is fully aware of its status as a weapon. Thel 'Vadamee is further led to question his faith by both the SPARTAN-117 and the Gravemind itself, as they both try to convince the Elite that the Covenant's belief on the Halos is a lie, revealing that the Halos destroy life, not save it. This information, as well the information of the imminent genocide of the Elites lead Thel 'Vadamee reluctantly joining SPARTAN-117 in the mission to stop the ring from being activated. The Gravemind sends both the SPARTAN-117 and Thel 'Vadamee to different location to help stop the Index from reaching its destination. SPARTAN-117 was sent to High Charity to retrieve the Index while Thel 'Vadamee was sent to the area where the Control Room of Installation 05 to halt the Covenant from activating the rings.

SPARTAN-117 then enters the middle of a conference of Truth. The Prophet of Truth, after escaping assassination, flees to the Dreadnought. John-117 chases him, killing many covenant on the way. He also witnesses the conflict between the Elites and Brutes. SPARTAN-117 saves a few marines along the way. Meanwhile, the Flood under the control of Gravemind crash into High Charity using In Amber Clad. When John nearly meets Truth, he finds Mercy on the ground being infected by the Flood; the Prophet tells the Spartan that Truth is going to Earth to "finish what the Covenant started". In his efforts to reach the Forerunner Dreadnought he has to fight his way through the Flood and the Covenant. After boarding the Dreadnought he leaves Cortana behind while he gets on the ship by boarding it through a large energy beam which serves as an energy supply for the High Charity.

Meanwhile, Thel 'Vadamee is teleported near Halo's control room. There, he finds many dead Elites, which were, no doubt, killed by the Brutes. With the help of a few deployed Elites, he fights his way to meet Rtas 'Vadumee, who is surprised to hear that the Brutes murdered the Councilors. They fight their way to a Scarab, where Sergeant Johnson is held. Johnson takes control of the Scarab and forcefully initiates an uneasy alliance between the humans and the Elites. With the combined efforts of Johnson and 'Vadamee, the Scarab breaches the Control Room doors by using the main energy cannon of the Scarab, and 'Vadamee enters the Control Room to confront Tartarus. In the Control Room, he hears the truth of the Halos directly from 343 Guilty Spark. Regardless of this disheartening revelation, Tartarus forced Miranda Keyes to activate Halo. Many Zealots and Councilors aid 'Vadamee in his final fight against Tartarus, and eventually after a harsh and ravenous fight, manage to kill him. It initially cost the Elites precious soldiers, mostly ranked Zealot, Councilor, or Spec Ops. Once Tartarus is defeated, Miranda grabs the Index just in time to stop Halo from firing, only putting it on a standby status, as said by 343 Guilty Spark. He informs them that all the remaining Halos can now be activated remotely from the Ark.

The Forerunner Dreadnought arrives at Earth with SPARTAN-117 onboard. He alerts Admiral Hood of his presence, and tells him that he is "Finishing this fight" when asked what he is doing on that ship.

In a scene after the credits, it appears that High Charity has been completely taken over by the Flood, as thousands of Flood spores are visible throughout the air, floating along the view. The Gravemind speaks of satisfaction of being free of his "empty grave", and suddenly Cortana appears as a hologram on a pedestal in the room. The Gravemind then states that there are questions that linger in his mind, which Cortana must answer. Cortana replies, "Alright. . .shoot!" The screen then turns black before any question is heard, signifying a possible, yet unlikely truce between the Flood and the UNSC, which, in any case, would not be expected to last or be held strong.