Spoilers are ahead for Halo season 2's finale.

Summary

• The Halo season 2 finale sets the stage for a thrilling season 3 with the return of Master Chief and Cortana's dynamic as well as the emergence of the Flood.
• The introduction of 343 Guilty Spark hints at story moments from Halo: Combat Evolved.
• The sacrifice of characters like Kai — and the dwindling numbers of Spartan-IIIs — create high stakes for Master Chief and humanity's future.

The Halo season 2 finale wraps up several threads, all while setting an exciting third outing into motion, especially where Master Chief's (Pablo Schreiber) story is concerned. The eighth episode, which is aptly titled "Halo," picks up where the previous installment left off. Makee (Charlie Murphy), the Covenant-raised human, and The Arbiter Var 'Gatanai (Viktor Åkerblom) are racing toward the Halo, thanks to Cortana's (Jen Taylor; Christina Bennington) quick thinking. Eager to stop the Covenant from reaching the Sacred Ring, iral Parangosky (Shabana Azmi) sends wave after wave of Spartan-III soldiers at the enemy fleet.

Elsewhere, Dr. Catherine Halsey (Natascha McElhone) and Miranda Keyes (Olive Gray) "blessed one" to the Halo.

The Monitor Explained: Master Chief Is Speaking To 343 Guilty Spark

The Halo season 2 finale opens with Master Chief speaking to an unseen someone (or something). Periodically, the episode will show flashes of the conversation: John sits in the near-dark with his helmet off. The episode's final moments reveal that the person John was speaking to isn't a person at all, but a monitor called 343 Guilty Spark. As advanced A.I. constructs, the Forerunner-built monitors serve several purposes. For their wisdom, monitors have been dubbed "Oracles" by the Covenant who are on their Great Journey. In Halo: Combat Evolved, Guilty Spark is tasked with maintaining Installation 04.

In Halo: Combat Evolved, 343 Guilty Spark immediately recognizes Master Chief as a "Reclaimer."

In Halo: Combat Evolved, 343 Guilty Spark plays a key role in the effort to contain the Flood after the Covenant troops (and the UNSC Marines) stumble upon the villainous parasite. Following protocol, 343 Guilty Spark enlists Master Chief's help in retrieving the Index — a device that allows one to activate the Halo's defensive measures. Cortana fills the Chief in on Halo season 3 dynamic.

The Flood Explained: Halo's Zombies Change Everything

The beginning of Halo season 2, episode 8, "Halo," sees Miranda Keyes investigating what she recovered from the secret Forerunner lab on Onyx. After unlocking the device, Miranda views its contents through a microscope. A fellow UNSC scientist enters the lab to ask Miranda all sorts of questions, grilling the Commander about her lack of prowess in the field of biology. While Miranda struggles to put together what the organism is, the UNSC scientist leaves the research area. Almost immediately, it's clear that the spores have infected her, prompting the unassuming scientist to violently kill her coworker.

The Flood can't be stopped — unless it's starved.

While Miranda safely handles the Flood specimen in the lab, the UNSC scientist spreads the parasitic infection throughout the base, compromising untold numbers of UNSC and ONI personnel in the process. In Halo lore, the Flood are the reason the Forerunners built the Halo array superweapon. The being can't be stopped — unless it's starved. To make matters worse, the Flood manifestations are connected by a hive mind, allowing them to share knowledge and act as one. Although an infected Laera attempts to contain the Flood by locking down the facility, there's likely no stopping Halo's biggest threat.

What Happens To Halsey & Miranda Keyes

For the majority of the Halo finale, Dr. Halsey is with iral Parangosky in the ONI command center. As the iral sends wave after wave of Spartan-IIIs to their deaths, she holds out hope that John-117 will beat Makee and The Arbiter to the Halo and claim the superweapon for humanity. When Master Chief realizes that Kai (Kate Kennedy) and Perez (Cristina Rodlo) are in imminent danger, he abandons his pressing mission to aid them. Afterward, John risks his life to save Cortana from the heavily damaged Covenant ship that Makee abandoned.

...the ONI control room is breached by the Flood.

Instead of swaying John to abandon his rescue mission, Dr. Halsey's curiosity gets the best of her — much to Parangosky's dismay. Not only does Halsey want the Spartan to save her precious A.I. construct, but she likely wants to encourage John's exploration of the Halo. Toward the end of the episode, the ONI control room is breached by the Flood. Halsey flees to Miranda's lab, but it's revealed that she's been infected. To save her estranged mother, Miranda puts Halsey in a cryo-chamber, hoping to stave off the infection's effects while she scrambles to find a cure.

Kwan Ha's Connection To The Forerunners & The Mother

Kwan Ha (Yerin Ha) has been plagued by visions of the looming Flood threat since Halo season 2, episode 1. While Kwan took episode 1's cave art to be a depiction of a monster from myth, she's swayed as the season progresses. After the Fall of Reach episode, Kwan sees visions of The Mother (Olwen Fouéré), a shaman from Sanctuary. While The Mother's origins aren't made explicitly clear, viewers get more insight in the finale. As Kwan is surrounded by Flood-infected soldiers, The Mother s her telepathically, saves her from death, and hints at Kwan's destiny as a "protector."

iral Parangosky is one of the Flood's many victims in the Halo season 2 finale.

Kai, Spartan-IIIs & The Future Of The Spartans In Halo

Over the course of Halo season 2, the Spartans' ranks have crumbled. First, Vannak (Bentley Kalu) was one of the characters Halsey's replacement, James Ackerson (Joseph Morgan), recruits Kai to his cause. Not only does he manipulate her feelings about John's competency, but he tasks Kai with training a new generation of soldiers: the Spartan-IIIs.

...the Spartan-IIIs allow ONI and the UNSC to trade lives for time.

While the differences between the Spartan-IIIs and Master Chief's cohort are vast and many, the key element is that Ackerson's soldiers aren't genetically augmented. Unlike Halsey's program, the Spartan-III initiative allows Ackerson to pull recruits from a much broader pool. In short, the Spartan-IIIs allow ONI and the UNSC to trade lives for time in the fight against the Covenant. In the finale, Kai sacrifices herself to destroy a Covenant cruiser. Although a few Spartan-IIIs, like Perez, survive, their numbers dwindled. Now, Master Chief is the only Spartan-II left standing (apart from the conflicted Soren).

Halo Season 3 Story Setup: We're Finally At Combat Evolved

Several huge plot points unfold in the Halo season 2 finale that set up a promising third outing. In saving Cortana, Master Chief allows the A.I. to merge with him again, setting up their game dynamic. The duo also crash-land on the Halo, which is presumably Installation 04, due in large part to 343 Guilty Spark's appearance on the Forerunner structure. Plus, the finale introduced the threat of the Flood. All of this to say, the key narrative elements from Halo: Combat Evolved are all in play, so Halo season 3 will finally adapt the franchise's original story.

All 8 episodes of Halo season 2 are now streaming on Paramount+.