Halo: Escalation Issue 21

Halo: Escalation Issue 21 was released on August 26, 2015 and was the twenty-first comic in the Halo: Escalation series.

Plot summary
On September 18, 2558 at 0007 MST, Song of Retribution is circling the main receiver of the Absolute Record's tracking station. Aboard the assault carrier, Jul 'Mdama and Doctor Catherine Halsey attempt to enter the installation. However, a slipspace portal opens nearby and the ship's helmsman loses control. Retribution is forced through the portal and it arrives inside a large chamber, where the carrier is held in place by a gravitational anchor. 'Mdama and Halsey decide to travel down to a platform below, where a Contender-class artificial intelligence awaits their arrival.

In one of Song of Retribution ' s hangar bays, Spartans Sarah Palmer and Holly Tanaka and Doctor Henry Glassman await their chance to leave the damaged drop pod they are hiding aboard. Glassman decides that they need to leave the carrier and find a local terminal, while Tanaka spots two nearby Type-44 Phantoms that they can steal. Nearby, a Sangheili orders several Kig-Yar crew members to break down the drop pod the humans are hiding in for parts to repair the carrier's hull. Meanwhile, several s are repairing the hull of the damaged Breath of Annihilation on a moon. Within a hangar bay of the carrier, several Sangheili Storm are arguing whether or not their ship and its crew were attacked by Spartans. Mercenary Ayit 'Sevi listens to the heated debate before entering a nearby Phantom that Spartan Gabriel Thorne is hiding in. 'Sevi decides to use use the ongoing argument as a way to instill chaos aboard the ship and initiate a mutiny. The mercenary wishes to have Thorne attack the Sangheili to create panic throughout the ship, though Thorne is reluctant to trust 'Sevi due to their previous encounter on Ven III. 'Sevi asserts that Thorne will never be able to find a way off the carrier if he does not trust him.

Meanwhile, 'Mdama, Halsey, and numerous Sangheili Zealots arrive at the platform and meet with the AI. Halsey addresses the ancilla and claims to be chosen by the Librarian to unlock the Absolute Record. Halsey requests to be escorted to the proper area to begin their work, but the AI expresses its doubts, especially pondering why the other humans feel the need to conceal themselves. The AI uses Sentinels to transport the drop pod the other humans are hiding in to the platform, where they are dropped down beside Halsey and 'Mdama. Both groups begin to argue, with Glassman questioning Halsey's decision to defect to 'Mdama's Covenant. Halsey tells Glassman to shut up, but the AI tells her that she has no authority to silence him. It decides to let each human have a chance to account for its presence at the installation, though Halsey asserts that there is nothing to discuss as she has the Janus Key. The AI intends take as much time as it needs to question each human, as it wishes to operate with total caution after one of its fellow Contender-class AIs made the mistake of not taking the same precautions during the Forerunner-Flood war.

Aboard Breath of Annihilation, Thorne has decided to follow 'Sevi's plan and he begins attacking the Sangheili, with 'Sevi directing Thorne around the ship. 'Sevi has Thorne go into hiding again, as numerous Sangheili and Kig-Yar soldiers begin searching for him. Meanwhile, Glassman states that he shares the same views as the AI, as he does not want the Absolute Record to be exploited. Halsey scoffs at this claim, but the AI orders her to remain silent. Glassman insists that the United Nations Space Command intends to use the Absolute Record in a way that is consistent with the Forerunners' intentions and claims that conflict will only get worse if 'Mdama's Covenant gains access to the installation. As Halsey and Glassman begin to argue, an impatient Zealot attacks a Sentinel, leading to all the constructs attacking the humans and Sangheili. The AI removes the platform from under the feet of the Sangheili with Tanaka, Palmer, and Glassman remaining on one platform and Halsey standing on another, while 'Mdama manages to grab onto Halsey's platform while his soldiers plummet to their deaths. The AI claims that a more direct examination is in order to decide who is the legitimate steward of the Absolute Record.