The survivors of the battle at Eridanus II limp back to Reach with their dead. The Master Chief blames himself for letting the Covenant get the Second Keystone, but Keyes chooses to focus on the lives he saved. Master Chief traps Halsey in one of her labs and activates a potentially lethal decontamination sequence, goading Cortana to take over his body in order to free her, but she makes it clear she can only shut him down. Satisfied learning of Cortana's limitations, he frees Halsey from the trap but makes it clear they are not on good terms.
Halsey becomes the victim of internecine conflict: she's used as The Scapegoat for the battle and Reassigned to Antarctica, with the SPARTAN program moved to Dr. Miranda Keyes' control. The deposition on her wrongdoings is interrupted when John bursts in and demands to know the truth about how he and the other SPARTANs joined the program. Halsey tells him: they were kidnapped as six-year-olds so that they could be trained and augmented in secret, and replaced with clones who would deteriorate and die in short order. This results in Miranda learning the truth as well: Keyes and Adm. Parangosky are eavesdropping on the deposition and she joins them just as her mother drops The Reveal. Kai, the only other SPARTAN with her pellet removed, becomes John's confidant; her first thoughts are of her parents, who believe her dead.
Makee (emphasis on the second syllable) will only talk to John-117, whom the Sangheili call "Demon." She confirms what John learned from the crazy homeless guy at the Rubble: that the two of them are "Blessed Ones," with the rare ability to operate Precursor technology like the Keystones.
Miranda takes over her mother's lab — despite some contretemps where the computers are only authorized to take orders from Halsey, resulting in an uncomfortable meeting between the two. At the Chief's behest, she grants him access to the original Keystone and wires him up with biomonitors. As John touches the Keystone, Makee also goes into seizure; the biomonitors attached to her confirm to Halsey, who is spying on the proceedings using a Borrowed Biometric Bypass she got from that meeting with Miranda, that her brainwaves are the same as John's. The two are given a vision of the massive Ringworld Planet Halo, the sacred ring the Covenant seek.
Tropes:
- Affectionate Gesture to the Head: While they've both experiencing the Halo vision, John brushes Makee's cheek with his hand.
- Armor-Piercing Question: "To save humanity at the cost of your own?"
- Bait the Dog: Halsey's apology to her daughter is only an excuse for a Held Gaze so she can get a retinal image of her eyes.
- Blackmail Backfire: Halsey tells Admiral Parangosky she has evidence of her own involvement in Halsey's crimes, but Parangosky points out that revealing that evidence would only get them both thrown into prison. Halsey has to swallow Parangosky's allotted punishment because at least it still gives her a chance to continue her research.
- Borrowed Biometric Bypass: Halsey arranges a meeting with Miranda so she can use specialized contacts to steal Miranda's retinal scan. Once Cortana hacks through the UNSC firewalls, it allows Halsey to monitor her experiments from her room.
- Death by Irony: John explains how the man responsible for all the failsafes in UNSC tech, having installed them because he never trusted technology to work properly all the time, ending up dying to the one system he neglected to check.
- Evil Mentor: Makee gives John some pointers on how to better interface with the Keystone, having had experience with similar artifacts in the past. It appears to be a trust-building measure, since they won't let her anywhere near it out of suspicion of her motives.
- Exact Words: When Halsey is asked about who else was involved with the immoral actions of the Spartan program (of which include Keyes and Paragonsky watching remotely), Halsey just says that people don't ask questions if they get results. A non-answer, but one that mostly satisfies the investigation while also avoiding the wrath of ONI.
- Failsafe Failure: John exploits a glitch in the decontamination sensors in Halsey's mobile lab to threaten her with a lethal dose of ultraviolet radiation, as a means to test if Cortana has the capacity to completely control him. Once he's satisfied she cannot, he releases Halsey.
- Internal Reveal: John, Miranda and Kai learn the true origins of the SPARTAN program. John also deduces, based on Cortana shutting him down last episode, that Cortana's intended purpose was to completely control him, even if she lacks that ability presently.
- Mood Whiplash: The episode opens with John sitting in silence, pondering his recent revelations and death glaring at Halsey. Then Kai grabs his arm, and we see she's screaming in agony on a bed next to John in a crowded and noisy sickbay.
- My Significance Sense Is Tingling: Makee can seemingly sense that John is about to activate the Keystone and becomes extremely agitated, nearly blowing her cover by shoving and then trying to stab the guard watching her eat with her finger blade. She lucks out when John touches the artifact and causes her to suffer a seizure, making it look like an outburst instead of an attempted murder.
- Oh, Crap!: Makee does a good job of hiding it from Miranda and John, but she is clearly worried when Miranda mentions that the UNSC intercepted the transmission she sent to the Covenant after attacking the human ship a few episodes earlier and are attempting to translate it from Sangheili to English because if they realize the voice in the transmission is hers, her cover will be instantly blown.
- Only the Chosen May Wield: A comparison between John and Makee's DNA shows that they share a single, very rare genetic marker that is found in no other individual on file, the likely reason they can use the artifacts. Miranda estimates that they are "two in a billion."
- O.O.C. Is Serious Business: In a culmination of events since the first episode, it's confirmed that Master Chief's erratic behavior is directly connected to his interactions with the artifacts, especially the extreme power of the second one. It has begun to take a physical toll on him where he can barely think straight, has panic attacks, outbursts and raised vitals. While some of it is connected to him removing his hormonal pellet and the buried secrets coming to light, Makee tells him she experienced similar physical symptoms dealing with numerous lesser artifacts and he has to confront all of that with the artifact in order to be stabilized.
- Properly Paranoid: John rightly suspects that Makee can't be trusted to use the Keystone, and so does Miranda. The latter even tells John that Makee may be trying to get John killed by encouraging him to continue interacting with the Keystone despite the obvious physical deterioration, though John persists anyway.
- Reassigned to Antarctica: Parangosky has Halsey reassigned to a private lab on the Barrier Moons. She gets to continue her research, but loses any actual authority she once had.
- Ringworld Planet: The final shot of the episode is a vision of John and Makee standing on a Halo, showing them that the "sacred ring" is a lot bigger than either knew.
- Secret Test: John's attempt to kill Halsey was actually testing how much control Cortana had over him. While she can put him into a stasis she can't control him as People Puppets; so once the trap was set she can't fix his mechanical jam on the doors. He never intended to kill Halsey, but it was also to let them both know what kind of mood he was in.
- Snipe Hunt: Makee gives the Covenant name of the planet where they've taken the Second Keystone, but only claims to know the human name of the star system where it's located. This, needless to say, doesn't narrow it down much.
- Standard Female Grab Area: Halsey pulls her arm free when an MP grabs her there, but of course she still has to accompany them.
- Synchronization: Due to their shared connection with Forerunner tech, Makee suffers the same symptoms as John when John touches the Keystone, despite being elsewhere in the base. Halsey notes that their physical readings are identical when John stabilizes and has a vision of the Halo, which Makee shares.
- To the Pain: John describes in detail how a lethal dose of UV radiation will kill Halsey, to motivate Cortana into stopping him.
- Try Not to Die: Miranda tells John not to die when trying to use the Keystone to find the companion artifact.
- Wham Shot: When John manages to fully connect with the Keystone, he and Makee are brought to a vision of them standing on a scenic horizon that curves up into the sky, the Ringworld Planet called Halo.
- The World Is Just Awesome: The vision of Halo is ethereal, with John and Makee standing on a precipice with a heavenly glow to it. There are not one, but two panning shots showing how the ring curves around, and the other side so far away it can barely be seen.
- You Called Me "X"; It Must Be Serious: Halsey calls Admiral Parangosky "Margaret" after realising she really is going to have her Reassigned to Antarctica.
