Makee and Chief connect through the artifacts and reunite in a vision of the Halo and they debate over how each side will use Halo as a weapon against the other. Makee is pulled away from the artifact but this event gives both sides Halo's location. The Arbiter manages to kill all Prophet loyalists on the ship, and Makee brands herself with the same mark as the Arbiter to confirm her loyalty.
With Cortana's data, Parangosky is able to track the Covenant fleet and know their numbers. She deploys a SPARTAN-III team against them and they are systematically eliminated. She orders another wave against Ackerson's objections. He starts looking deeper into the data spike simulations and realizes it's a Doomsday Device that could wipe out the Covenant fleet, most of the star system and Halo. There will be no survivors.
Chief is confronted by Captain Briggs who orders her men to shoot him, but he talks them down and Kai knocks out Briggs. Cortana leads Chief and Kai to Ackerson, who is shaken by recent events and is compelled to expose Parangosky's plans before leading them to Chief's armor. Kai knows the SPARTAN-IIIs are on a suicide mission, but is compelled to lead them since she helped train them and feels responsible for their fate. Chief needs to reach Halo before the Covenant do.
Halsey, Miranda, and Kwan explore the Forerunner alcove and Halsey reveals that a puzzle was left behind for the right people to unlock. She had gotten as far as finding genetic markers left behind, which instigated her involvement with the Spartan program. Miranda had unlocked more of the puzzle through applying linguistics to Halsey's math, and Kwan is able to trigger a star map set at the time of the Forerunners to open a doorway to a Forerunner city. Investigating a lab, they see a Forerunner body, but a disturbance incites them to leave, though not before Miranda recovers another artifact that the dead Forerunner was holding.
Chief is back in his armor and meets with Perez. There are many things at stake and they have separate missions, but offer encouragement. Chief goes through the base in full armor letting everyone know he is back, which causes Parangosky to have Ackerson arrested. Chief takes a Condor and travels to the site of the battle, but his target is further in the distance: Halo.
Tropes:
- Adaptation Distillation: The SPARTAN-IIIs in the main canon were intended to be expendable and their missions were considered suicidal, but that was a function of putting them in lopsided battles as cannon fodder. That trait is exaggerated here - while they were totally wiped out in canon barring those pulled to work on other objectives, here, their missions are intentionally designed to kill them the minute they are completed and Parangosky is throwing all of them at the Covenant at once with the hope that at least one squad will succeed.
- Adaptation Origin Connection: Halsey reveals that one of the containers in the Forerunner caves on Onyx had two genetic samples: one theirs, the other human. The Spartan program was partially an excuse for her to seek out candidates that share any sort of similarity between them. While in canon, Halsey did view the Spartans as an excuse to explore other scientific curiosities and had experience studying Forerunner ruins, that specific link between them is original.
- Armor-Piercing Question: After Chief points out that Kai was the one who chose to believe Ackerson's lies, she counters that she made a mistake. She then asks if Chief ever did. He doesn't answer immediately, but when he gets a chance to see Vannak's old armor, he more or less confirms that mistake was failing to protect his brother in arms.
- Armor-Piercing Response: Kai calls Chief out for lying to Silver Team about their mission authorization during "Visegrad" saying he put everyone in danger. Chief bluntly responds that it was Kai who chose to believe the people who were lying to them from the beginning, and absconded with their armor.
- Borrowed Biometric Bypass: Threatened, though not actually carried out. When Ackerson — being held in a Neck Lift by John — reveals that the SPARTAN-IIs' armor is behind a biometric lock, Kai observes that they will need his face to open it. John dryly asks if it still needs to be attached to him.
- Curb-Stomp Battle:
- The first wave of SPARTAN-IIIs are wiped out by the Covenant fleet before they can even manage to launch a single boarding party.
- The SPARTAN-II trainees were subjected to one as a test of their willpower as youths. Now an adult, Soren turns the tables on a similar battle against potential recruits, including his son.
- Dramatic Irony: Miranda identifies the Forerunner facility as a laboratory and translates the symbols on the door to mean "growth" in a negative context. When a tremor cracks the vials within and triggers a lockdown, they just barely escape. The star map outside then changes, star systems turning red one by one. Halsey interprets this as the expansion of their empire, but Kwan clearly has some sense of what it means and what is coming, choosing to run like hell. Audiences familiar with the Halo franchise know full well what this "growth" is referring to: The Flood.
- Earth-Shattering Kaboom: Ackerson analyzes Parangosky's spike code and realizes its intent is to trigger a fusion core overload in Covenant ships. He then scales up the simulation to planetary scale, and the blast is sufficient to wipe out a planet. Then he scales it up again to an entire solar system, which it obliterates.
- Entertainingly Wrong: The star map is reverted to the time of the Forerunners, Halsey notes that numerous locations start glowing red and assumes this represents their growing empire. Kwan has a strong feeling otherwise. Anyone familiar with Halo lore knows what this really is.
- Even Evil Has Standards: Ackerson may have reluctantly sacrificed Reach, but even he sees throwing the entire SPARTAN-III complement at the Covenant in the hopes that just one breaks through the line and completes their mission to be beyond the pale.
- A Father to His Men:
- Captain Briggs orders a team to shoot an unarmed and non-hostile Master Chief. Chief looks at them in the eyes and challenges their commitment to following orders versus doing the right thing. The marines back down and tell Briggs she will have to do it herself.
- Kai refuses to allow the SPARTAN-IIIs to go on a Suicide Mission without joining them, because she helped train them.
- A Downplayed case for Ackerson, considering he was willing to send the SPARTAN-IIIs on a Suicide Mission and considers them his "life's work," but he's not willing to throw all of them away in a hopeless strategy.
- Hard Light: A light bridge is generated between the lab entrance and the door to the antechamber overlooking the Forerunner city. Miranda is obviously wary, as that's not tech the UNSC has access to, but Halsey confidently takes the first step.
- Heel Realization: Ackerson comes to realize just how callous Parangosky is when she orders every SPARTAN-III to be thrown at the Covenant, willing to sacrifice them all for the chance of just one completing the mission.
- I Coulda Been a Contender!: Soren actually has fond memories of his Spartan training, however brutal it was, because it represented the friendships he made and the power he was promised. Laera realized that despite the life he has built he still regrets not achieving what he could have been, and secretly hopes Kessler could go further.
- Indy Escape: When containment in the lab is compromised and a lockdown begins, Miranda, Halsey, and Kwan have to flee back across the light bridge and into the main chamber before the bridge disappears and the door seals shut. Halsey is distracted by the sight of the Forerunner city, but Miranda drags her through just in time.
- Instant-Win Condition: The data spike the SPARTAN-IIIs were told would shut down a Covenant cruiser is actually designed to turn their fusion reactor into a Weapon of Mass Destruction, one that can destroy the better part of an entire star system. Parangosky doesn't care how many soldiers it takes, she just needs one to deliver the spike and the entire Covenant fleet will be wiped out, along with the Halo.
- Manipulative Bastard: When Ackerson confronts Parangosky and says he's going to take her down, she makes him realize that she'd been playing him the entire time so that the responsibility for the Fall of Reach, the creation and sacrifice of the SPARTAN-III program, and any potential fallout from the battle over the Halo will all fall on him while her hands stay clean.
- Mark of Shame: Makee brands herself with this, just as the Arbiter had, to symbolize their shared connection to each other and the Ring.
- Mistreatment-Induced Betrayal: While Ackerson was already not on board with Parangosky's plan, the reveal that she fully intends to throw him under the proverbial bus as the designated fall guy should things go sideways makes him more inclined to aid the Chief.
- My Greatest Failure: Chief confides in Kai that his inability to save Vannak's life is this, as he feels responsible for not doing enough to save him.
- Mythology Gag:
- John confidently makes his way through the base on Onyx, despite never having been there before, because Cortana is marking the way forward with blue lights while blocked-off paths are marked in red, much like the games keep players on track with visual cues.
- While the symbols that Halsey and Miranda see in the Forerunner ruins aren't given exact definitions, since Miranda only has the barest understanding of the language, the bottom symbol is the one for "Guardian" while the top one represents the Flood. Miranda correctly, if vaguely, interprets the former as a negative context and the latter as "growth," not that they take the hint.
- Parangosky's plan with the data spike that actually turns a Covenant cruiser into a bomb that can destroy a solar system is similar to a battle in the novels where a nuclear bomb was detonated in a gas giant to escalate a fusion reaction that destroys a nearby Covenant fleet. It having the potential to destroy Halo is also the climax of the original Halo: Combat Evolved and causing an overload of the Pillar of Autumn's reactor to destroy the ring.
- Neck Lift: When the Chief gets his hands on Ackerson, he lifts him up by the throat.
- Never Found the Body: Miranda heard about her father's death, but held some hope that he was present among the scattered survivors somewhere. Halsey had to mournfully tell her that, no, she was right around the corner when it happened.
- No MacGuffin, No Winner: Parangosky intends to destroy the Halo since the likelihood of taking it from the entire Covenant fleet is practically non-existent.
- "Not So Different" Remark: Ackerson questions Parangosky using the SPARTAN-IIIs for a mass assault, sacrificing as many as needed to get the job done. When Chief questions his current spark of conscience, he says the IIIs are his "life's work" and Chief only replies that he's heard that before, as Halsey often said the same about the SPARTAN-IIs.
- Only the Knowledgable May Pass: The Forerunner ruins seem to be set up in this fashion. The first test is mathematic, to test that visitors at least have a basic understanding of what they're looking at. The reward for that is human and Forerunner DNA, a hint as to what is needed to complete the test. The second is linguistic, to test that visitors understand the deeper meaning of the location, at least to some extent, which rewards the key needed to unlock the lab. Finally, the third test is astrological, reproducing the sky as it was during their time, and requires someone capable of using Forerunner technology. It's not perfect, because only Kwan seems to get the danger of what is stored there, but Halsey and Miranda were at least competent enough to get the intent of the first two tests.
- Promoted to Scapegoat: Ackerson realizes this is him when Parangosky points out that if people learn Master Chief is alive, it will bring up questions about the Fall of Reach and who knew it was coming.Ackerson: Well, we don't have to worry about that.
Parangosky: Did you say "we"? You were the one in charge.
Ackerson: Acting on your orders.
Parangosky: But, I'm not even in the ONI. - Restart the World: Makee believes the Halo contains the seed of life and that she and the Chief can start a better world there, since both humans and the Covenant will only use it to destroy. She's technically not wrong, just ignorant as to why that function exists.
- The Reveal:
- The spike the SPARTAN-IIIs are intended to inject into Covenant ships doesn't just disable them, it triggers an overload that can wipe out an entire solar system and, more importantly, the Covenant fleet that happens to be there.
- Kwan also has the ability to activate Forerunner artifacts, her touch activating the puzzle in the Forerunner ruins. But while the Chief and Makee dream of the Halo, Kwan dreams of the empire that was and what laid it low.
- The SPARTAN-IIIs are meant as an expendable stop-gap as ONI is training a true successor batch to the SPARTAN-IIs — also recruited as children and put through hellish training.
- A Forerunner body is found inside the Forerunner complex. Other than elongated limbs, Halsey notes how similar its appearance is to a human.
- Screw This, I'm Outta Here: Halsey and Miranda are star struck to be inside the Forerunner lab, but when a disturbance causes whatever is being studied to risk breaking containment, the lab suddenly goes into lockdown and they barely escape with their lives. The star map in the main room then changes, showing an ominous red spreading across the galaxy. Halsey interprets this as the spread of the Forerunner empire, but Kwan is the first to get the hint and bolts out.
- Training from Hell: Soren describes how the Spartans as kids were sent down a corridor to attempt to get past adults with truncheons. The intent wasn't to actually succeed, as they hadn't been augmented at that point, but to weed out who would run and who would take the beating, he and the young members of Silver Team falling into the latter category. He nearly lets Kessler do the same, since he believes Kessler will learn the same lesson, but ultimately intervenes after being chewed out by Laera.
- War Is Hell: Discussed by John with Ackerson, who points out that in this conflict, everyone pays a price. Now it's Ackerson's turn if he wants to ensure Parangosky is stopped.
- Well-Intentioned Extremist: Parangosky is willing to sacrifice every SPARTAN-III if it means stopping the Covenant here and now, but she's absolutely right that should the Covenant gain control of the Halo, there would be no next battle. Chief even agrees with her on that point.
- Wham Shot:
- In the Onyx Forerunner caves, Kwan managed to uncover the final piece of the puzzle and a door opened up, allowing them access to a deeper Forerunner complex. Halsey then triggers a blue Hard Light bridge which leads them to a lab, and they also get a glimpse of a greater Forerunner city before having to retreat.
- Just moments after, the three get a glimpse of what Halsey and Miranda assume is the Forerunner Ecumene's expansion. Kwan sees it for what it really is and runs. The Flood is coming.
- What the Hell, Hero?: When Soren describes the purpose of the training to Laera and believes Kessler will benefit from going through the same ordeal, Laera calls him out on subjecting their son to such brutality, and accuses him of trying to recapture the feeling of being a Spartan, even if it means doing so vicariously through their son.
- You Called Me "X"; It Must Be Serious: As the light bridge disappears from under them, Halsey stands staring in wonder at the city below them, ignoring Miranda's increasingly-desperate pleas to flee until she calls her "Mom" instead of "Halsey." She stares at her daughter in surprise for a brief second, then runs like hell.
- Villain Has a Point: Chief is by no means a fan of Parangosky and her extreme methods, especially her willingness to send all the new Spartans to die in a horrendously one-sided battle, but he agrees with her assessment that the Halo can't fall into Covenant hands because he intrinsically knows it can wipe out humanity, and tells Kai to plant the spike and detonate everything as a last resort if all else fails.
- Zerg Rush: Parangosky throws wave after wave of SPARTAN-IIIs at the Convenant because she needs just one trooper to make it through to deliver the data spike that will wipe out the entire star system.
