Halo season 2 finale episode ending explained: What is The Flood?

Earlier episodes in season 2 teed up the conflict to come in the last episode, with Master Chief (Pablo Schreiber) doing everything he could to stop the Covenant from reaching the Halo. Elsewhere, Makee (Charlie Murphy) pledged her commitment to the Arbiter, with the pair solidifying their bond.

The final episode didn't disappoint either, introducing the Flood, seeing John finally going face to face with the Arbiter, and an ending that very much sets up the future of the show.

Recently speaking to RadioTimes.com about the potential for more episodes, showrunner David Wiener said: "Halo has so many stories to tell, so many worlds to explore, so many characters, and I think that's really the amazing thing about it as a video game property - it brings character in a way that is really special.

"Where we conclude this season is about opening another door to those possibilities."

Here's exactly what went down in the finale episode of Halo season 2 - and how it sets up potential seasons for the show.

Halo season 2 finale episode ending explained: What is the Flood?

The Flood is a species of highly infectious parasitic organism that turn human beings into zombie-like creatures. Fans have been waiting for the Flood to be introduced for some time, with that moment beginning at the start of the season 2 finale.

After Miranda Keyes (Olive Grey) and her mother Catherine Halsey (Natascha McElhone) retrieved a mysterious artifact from the archeological site, Miranda sets to work analysing it. However, she's interrupted by (let's face it) a pretty annoying colleague named Janine.

Despite Janine insisting she hadn't touched the artifact, she soon starts to exhibit strange behaviour, before going absolutely wild and stabbing a colleague in the neck with a pen, making it very clear that, not only was she lying, but something is very, very wrong. Enter The Flood.

Elsewhere, Kwan-Ha (Yerin Ha) and Soren (Bokeem Woodbine) pledge to rescue Laera (Fiona O'Shaughnessy) and Kessler (Tylan Bailey). The pair are imprisoned, with Kessler attempting to speak to a lady imprisoned with them.

As Laera tells him to stop bothering her, something feels wrong. Sure enough, we're shown the lady's face and it's clear she's suffering from gruesome symptoms much like our old friend Janine. They don't know it yet but clearly they're in trouble.

Luckily, Kwan and Soren are on their way. Unluckily, they don't know what they're walking into and what they're encountering when they see people frozen in their tracks. One of the infected manages to squeeze through the bars towards Laera and Kessler. Soren and Kwan get there just in time to rescue the pair of them.

When Halsey contacts Miranda, she reveals that the artifact they brought back from the archeological site was a sample container containing a parasite. Suddenly, the consequences become very clear as more and more crew begin turning into zombie-like creatures and attacking humans. Chaos quickly breaks out.

While trying to get Soren and Kessler to safety, Kwan runs out of ammo. Preparing to die, she instead sees The Mother (the Shaman from Sanctuary who we keep meeting throughout the season) in a vision. She holds the creatures back as Kwan escapes. The Mother finally calls the parasite by the name fans of the game will recognise – The Flood.

After their realisation, Miranda and Halsey argue over The Flood – with Miranda describing it as a biological catastrophe. However, when Halsey freezes, Miranda realises she's been infected. Miranda quickly puts her mother into stasis, though, saying that it should stop the progression and she promises to bring her back. Her fate is left uncertain.

Laera isn't so lucky, though. She sends Soren and Kessler on their way, locking herself away from them and revealing that she has also been infected. As Soren calls for her, she backs away from the door, telling him one last time that she loves him, with the pair later mourning her loss.

Is Kai dead?

It certainly seems so, with Kai (Kate Kennedy) sacrificing herself in a blaze of glory for the sake of her teammates and the battle as a whole.

We pick up with Perez (Cristina Rodlo) and Kai when they're preparing for battle. They're tasked with driving a spike through the huge Covenant ship, not knowing at this point that they're basically being sacrificed. From the get-go, they're being attacked on all sides with their ship blown apart and being forced to use the thrusters on their suits to stay in formation. As they land for a moment to take in the situation, they spot the huge Covenant assault carrier.

Meanwhile, Admiral Parangosky (Shabana Azmi) contacts Master Chief to inform him that a single vessel is bound for the Halo and that it's crucial that he reaches it first. He accuses her of deciding who to save and who to sacrifice, cutting his comms and making it clear that he'll follow his own orders.

Kai and Silver Team face an ambush, with it being made clear that the Covenant know their plan. It's an onslaught from the Covenant, with Kai requesting back-up – but it's clear they're fighting to buy Master Chief time. Quickly, John makes a decision – to save Silver Team, defiantly telling Parangosky: "You have no idea what I can do."

Makee (Charlie Murphy) grills Cortana about John, concluding that her loyalty to him is a problem, with Cortana (Jen Taylor) soon realising that Makee plans to erase her. Establishing that she and Cortana are the same, that they can "both see the future", Makee suddenly destroys Cortana's software, with the AI disappearing.

Perez is shot in battle and she urges Kai to not let her death, her "one way ticket" into battle, be for nothing. Immediately after, Kai lays eyes on the Chief razing down Sangheili in full hero mode. He assures Kai that he won't leave anyone behind (a promise that ages rather badly).

Kai manages to hijack a Covenant Corvette, sacrificing herself to crash it into the main Assault Carrier.

How does season 2 episode 8 set up a potential season 3?

Halo season 3 hasn't been confirmed yet, but the final scenes of season 2 certainly set up the potential for more episodes.

Parangosky says that the Covenant have reached the Halo, and urges Halsey to talk to John. She quickly realises that he's following Cortana on a breaking ship in the hopes of saving her and she defies Parangosky's orders to give him the best option to get on board the ship.

He manages to get on board and hears Cortana in the ship's systems, as she had nowhere else to go after her hardware was destroyed. She tells him that the only possible outcome is the pair of them being destroyed – but he's got another surprise up his sleeve.

John wakes up in the Halo ring world with Cortana, and the pair search for Makee. Cortana asks why they're there, with John answering: "This is where the fight is."

John finally finds Makee and the Arbiter, with a brutal fight ensuing. The Arbiter knocks John to the ground, but of course he rises back up. With a new wave of strength, he throws the Arbiter to the ground before finally killing him.

Makee tells John that, wherever he goes, war will follow. She claims that the ring will allow for peace – with John of course telling her he can't let that happen. Cortana interrupts, alerting him to a distinct rumbling. Makee tells John there's a lot left for him to find out about the pair of them, telling him: "I'm a demon too."

The final scenes of the show see John speaking to someone, ultimately shown to be the Guilty Spark, the caretaker of the Halo ring. The Guilty Spark tells John the Halo has been waiting to him.

There's so much more a potential season 3 could explore now, particularly John's dynamic with the Halo, now confirmed to be a living network. With John attempting to warn the Halo about Makee, presumably the pair will have to continue their fight for the Halo – but who will win?

Halo season 2 is available to stream on Paramount Plus now. Check out more of our Sci-Fi coverage or visit our TV Guide and Streaming Guide to find out what's on.

Try Radio Times magazine today and get 10 issues for only £10 – subscribe now. For more from the biggest stars in TV, listen to The Radio Times Podcast.