After forfeiting their lives to fiery oblivion, two action figures of the Halo series of games' principal characters the Arbiter and Master Chief having inexplicably come to life in 2008 find themselves in a parody of Stanley Kubrick's 1968 film 2001: A Space Odyssey -- a cargo ship traversing deep space, somehow taking place on the multiplayer stages of Bungie and 343 Industries' Halo: Reach for the Xbox 360. Chief, believing himself to be the ship's artificially intelligent robot PAL-9001, in a mission to discover the purpose of life, awakens the Arbiter, who suffers from amnesia and disturbing images of past tragedies.

Recently awakened aboard the Cargo Ship Truth and Reconciliation, Arbiter and Cortana look to PAL for answers as to why exactly they're on board.

In spite of PAL's unfounded misogyny, Cortana attempts to befriend the robot for the sake of the success of the crew's mission. With the two often at odds, Arbiter struggles with keeping the peace as well as his paranoia in light of the lethal contents of the ship's cargo bay and hallucinations of a mysterious stalker.

PAL reveals the cause of the ship's high alert status to be the imminent failure of a critical component of the ship's communications system.

Cortana makes the executive decision as the mission's Captain to deactivate PAL, believing the assistant artificial intelligence system to be a significant risk to the lives of the crew. Arbiter's torn between his odd-couple friendship with the robot and his respect for Cortana as his friend and superior. Meanwhile, PAL may have other plans.

Arbiter attempts a life-or-death negotation with PAL.

After PAL proves itself to be extremely dangerous, Arbiter takes drastic measures to disable the robot.

With the ship hijacked by deadly Space Allen soldiers obsessed with violating the rear ends of all lifeforms throughout the universe to death and led by the terrible alien king Xanthar, Arbiter is forced to fight or die.

The '2001: A Space Odyssey' arc is over. Having awakened from their dream states, the toys find themselves alive and together once again within the confines of their owner Jon's bedroom. Chief's happy. Arbiter, on the other hand.

The toys are back inexplicably in Jon's room after being dead for four years. While Chief searches for Jon's copy of Halo: Reach so he can play it and troll people online, Arbiter uses Jon's computer and internet connection to catch up on current world affairs.

More is revealed from the fast-forward in time seen in the first episode of this season. In the present day, Arbiter continues his search for purpose while Chief seeks means of obtaining the Xbox One X and the Master Chief Collection.

As the toys continue to seek their purpose, an enemy approaches.

Master Chief gets he and Arbiter into big trouble with the Terms of Service Enforcement and Response Squad. A formidable new foe performs a field test of an extremely dangerous malware tool.

Adam and Kylie form an uneasy alliance in leadership of both Kylie and Clyde's hacker armies, the latter leader now having been taken out of play. Feeling that TOSERS has ruined the Halo Reach online experience, Chief decides he's had enough with the confines of Jon's bedroom.

The Arbiter and Master Chief deal with a disturbing turn of events since Jon's return to the house. Adam moves forward with a secret and terrible plan. Claire recalls her last meeting with the Arbiter.

Kylie wrestles with the loss of her clan and relationship with Adam in handling her partnership with him gone awry. The toys discover that Claire's hosting an online event on Halo Reach in memorial of them, believing them to be dead. Adam, now one of the world's most powerful crime lords, plots a number of attacks, one involving a devastating cyber-weapon.

Cody completes Hate Machine for Adam, a cyber-weapon of mass destruction in the form of a program. Arbiter and Chief make an effort to stop him, paying a price they're not prepared to, and make discoveries there's no turning back from.