The War Between the Land and the Sea episode 5 ending explained: Why did Kate pull a gun in the post-credits scene?

The War Between the Land and the Sea is a five-part Doctor Who spin-off miniseries created by Russell T Davies. It premiered on BBC One and iPlayer, with episodes releasing weekly from December 7, 2025, and the finale on December 21.

This climate-crisis story reimagines the classic Sea Devils as Homo Aqua, an ancient aquatic species awakened by ocean pollution. The series stars Russell Tovey as UNIT staffer Barclay, Gugu Mbatha-Raw as Homo Aqua envoy Salt, Jemma Redgrave as Kate Lethbridge-Stewart and Alexander Devrient as Colonel Christofer Ibrahim.

Episode 4 ended on a cliffhanger with an assassination attempt on Kate that killed Ibrahim instead. In the finale, Episode 5 “The End of the War,” Kate's grief spirals, leading to the post-credits moment where she confronts a jogger littering on the beach with a plastic bottle. 

She demands he "pick it up," while pointing her loaded gun and screaming the command in rage, but the screen turns black before she pulls the trigger.

This outburst reflects her breakdown from losing Ibrahim, overmedication and frustration with humanity's environmental negligence, the very issue that sparked the war with Homo Aqua.

The War Between the Land and the Sea episode 5 ending explained: Homo Aqua's defeat and retreat to the trench

Episode 5, "The End of the War," begins with Homo Aqua luring and eating neighbourhood dogs on a beach, defending it as equivalent to humans fishing. Negotiations strain as Kate, haunted by hallucinations of the deceased Ibrahim, struggles to focus.

Kate visits her counsellor, requesting double the medication. When refused and threatened with being signed off work, she blackmails the counsellor with knowledge of her affair, securing the prescription. 

Meanwhile, Barclay, surviving deep water thanks to Salt, experiences physical changes: headaches, whistling ears and lung pain eased only in water. Confined for safety, he faces poisoning attempts but nightly escapes to the ocean, calling for Salt.

Homo Aqua threatens to melt ice caps. Salt signals "Accord" to Barclay, pausing hostilities. Corpses wash ashore worldwide as "Severance,” a human-engineered virus deployed secretly by generals and the Prime Minister, kills 90% of Homo Aqua by preventing scale shedding.

Resistant survivors exist "as if by design." Salt declares humanity victorious in this "inconvenience," not war.

Homo Aqua seals their technology deep underwater. Salt warns water will avenge wrongdoers, shown in flashes of drownings for the genocide's architects. The proposed Accord, a hybrid transformation for interspecies unity, is revoked but Barclay's scans reveal brain changes linked to it.

The negotiation tank shatters, symbolising broken peace. Kate rescues Barclay from protesters and drives him to the coast, set to David Bowie's "Heroes." He reunites with Salt, gains gills through their kiss and swims away as a hybrid.

What did the post-credits scene mean for Kate in The War Between the Land and the Sea?

The post-credits cliffhanger shows Kate alone on the beach post-Barclay's departure. Spotting a jogger discard a plastic bottle, she politely asks him to pick it up. He ignores and insults her. Kate draws her gun, repeating "Pick it up"  desperately until screaming in fury.

This scene captures Kate's profound unravelling. Her grief over Ibrahim's death, compounded by hallucinations and self-medication through blackmail, has left her unstable. 

The littering act symbolises humanity's casual environmental destruction- the root cause of Homo Aqua's emergence and the conflict. 

Without the Doctor's guidance, Kate's rage blends personal loss with broader anger at human flaws, hinting at a darker, more ruthless future for the UNIT leader.

What does "Severance" mean in The War Between the Land and the Sea?

Severance is the covert biological warfare program orchestrated by high-ranking officials, including General Gunsberg, General Dussolier and Prime Minister Shaw. It involves engineering a virus that prevents Homo Aqua from shedding their scales, resulting in widespread deaths. 

Deployed secretly by infecting Barclay, who transmits it to Salt and thus her species, it results in genocide, killing 90% of Homo Aqua and forcing their surrender. The program highlights humanity's fear-driven aggression over diplomatic solutions.

What is "Accord" in The War Between the Land and the Sea?

Accord represents Homo Aqua's proposed path to harmony: a biological process that allows humans to join them underwater by granting gills, enabling interspecies unity and celebration. 

Signalled worldwide by Salt, it's ultimately revoked after Severance's devastation, as Homo Aqua retreat in terror. However, it partially succeeds in Barclay, whose brain chemistry changes activate the transformation, allowing him to grow gills and live with Salt.

What to expect next from Kate Lethbridge-Stewart in Doctor Who?

Kate's grief-fueled decisions, including blackmail and the gun incident, tease a complex arc upon her return. She could emerge more corrupted, ruthless or in need of redemption, potentially at the hands of the Doctor or UNIT superiors.

The series sets up ripple effects, such as ongoing human-Homo Aqua tensions and Barclay's hybrid existence, which influence future Doctor Who stories.

The War Between the Land and the Sea is streaming in full on BBC iPlayer in the UK. It arrives on Disney+ internationally in early 2026.

There is no official confirmation for Season 2 yet.

Stay tuned for more such updates!