The War Between the Land and the Sea ending explained: What is Severance?

Warning: Major spoilers ahead for The War Between the Land and the Sea episode 5.

The War Between the Land and the Sea has aired its devastating final instalment, with episode 5, The End of the War, brutally reminding us that war has no winners.

The finale episode of Russell T Davies's climate-focused series shows the impact of humanity's murderous actions towards Homo Aqua, as well as Salt (Gugu Mbatha Raw) and Barclay's (Russell Tovey) bittersweet ending.

Plus, after much teasing from the showrunner, that post-credits scene has finally aired, showing Jemma Redgrave's Kate Lethbridge-Stewart in crisis after the war and the loss of Christofer (Alexander Devrient).

So, here's exactly what went down in the finale episode of The War Between the Land and the Sea.

The War Between the Land and the Sea ending explained: What is Severance?

Severance turns out to be a plot to murder 90% of Homo Aqua's population by means of biological warfare, thereby 'winning' the war for humanity by committing genocide.

The plot was orchestrated by General Oscar Gunsberg (Stewart Alexander) and General Dominique Dussolier (Barbara Probst), with Prime Minister Harry Shaw (Vincent Franklin) also involved, as well as the officer stationed outside of Barclay's room, who is spying on him.

The officer reports that he sees Barclay leave his apartment every night to look for Salt - but that she can't find him. Dussolier suspects that's down to the bafflers that her government has placed in the water to disrupt the Homo Aqua's communications, and orders them to be paused, meaning Salt is able to hear and get to Barclay the next night.

Meanwhile, Gunsberg's agents spike Barclay's drink and inject him with the virus in his sleep, meaning he unknowingly passes it onto Salt when they kiss. Salt brings the virus back to her people, later realising what's happened when it's too late, before telling Barclay: "The virus brought fire to the world of water. And we burnt."

What happened to Homo Aqua?

With their people all but destroyed, Homo Aqua surrender to humanity in a heartbreaking scene between Salt and Barclay, with the pair still acting as ambassadors for their species.

In an act of revenge, Salt tells the humans in the room that she knows who orchestrated the genocide, and that the water will eventually come for them - and we see flash-forwards of the imminent deaths of Gunsberg, Dussolier, and Shaw. She also reveals that Homo Aqua have hidden their technology far beneath the ocean, where humanity will never reach.

On behalf of humanity, Barclay offers a "haven" to Homo Aqua in the Mariana Trench and says they will be protected. Speaking for Homo Aqua, Salt says they will accept the offer - but that they are under no impression humanity will keep them safe.

Before leaving, she tells him a devastating truth: that Homo Aqua will do whatever humanity wants, because they are terrified. Finally, the water tank in the Empress Hall cracks and shatters, signalling the final crack in the relationship between Homo Aqua and humanity.

What happened to Barclay - and what was Accord?

Earlier in the episode, Salt attempted to convince Barclay to ask Homo Aqua for "Accord" - but she didn't explain what it was until the end, when she tells him: "It's a way of two species joining and celebrating, which is now lost."

However, clearly it's not entirely lost.

Kate receives a phone call from Barclay's doctor, who has Barclay's brain scan lighting up his computer, with the word "Accord" next to it. It appears that Barclay's brain chemistry has changed and, when Kate drives him to the coast, he races to Salt's side.

When she touches him, he founds he has grown gills, and the pair swim off into the ocean, safe in the knowledge that, despite everything that has happened between their two species, at least they can now be together.

What will happen to Kate?

In the post-credits scene, Kate is walking away from the beach where she leaves Barclay, when she sees a runner who litters, dropping a plastic bottle on the sand.

When he refuses to pick it up after multiple requests from Kate, she pulls out a loaded gun, demanding: "Pick it up."

As we saw earlier in the episode, Kate is struggling after the devastating loss of Christofer, leading her to make increasingly questionable and damaging decisions (not least, blackmailing her psychiatrist in order to increase her prescription dosage).

Clearly, Kate needs to take some time to heal - but whether she will allow anyone to enforce this is another matter. Perhaps she needs a voice with higher authority than her - someone like the Doctor...

The War Between the Land and the Sea is available to stream on BBC iPlayer.

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