An unassuming family man is accidentally recruited to help save the planet from a war between humans and an ocean-dwelling race in the Doctor Who spin-off, The War Between the Land and the Sea.
Low-level UNIT operative Barclay (Russell Tovey) is selected by Aquakind ambassador Salt (Gugu Mbatha-Raw) to represent the human race in a summit at Empress House in London, a UNIT (Unified Intelligence Taskforce) installation on the banks of the Thames.
Basically a taxi booker, “He’s an ordinary man being thrown into an extraordinary world simply because of paperwork,” showrunner Russell T Davies described of Barclay in Empire magazine.
The only human she can trust, the connection Salt forms with Barclay “is wonderful and unexpected, and beautiful,” Tovey explained to Empire. Their developing relationship is at the heart of the story.
First seen emerging from the seas in the 1972 Doctor Who story The Sea Devils, Aquakind are now known as Homo Aqua. They are furious with humankind for polluting their ocean habitat.
UNIT Chief Scientific Officer Kate Stewart (Jemma Redgrave) issues a statement on the plans for the summit in a video released as part of a cryptic challenge on the official Doctor Who website.
“This is a worldwide alert for all branches and divisions of the Unified Intelligence Taskforce. Today is a turning point in history. All across the planet, Aquakind have revealed themselves and our world has changed forever. The public will be scared. And when the human race is scared, we do terrible things. It’s up to us to keep the peace, to hold the line as we try to negotiate a way forward. Right now, two floors below me, The Empress Hall is being prepared for diplomatic talks. Aquakind will send an ambassador. We will meet officially for the first time, and the world will be watching. We cannot predict what the coming days will bring, but there will be unprecedented demands on all of us. Ordinary people will be tested like never before. Heroes will be forged. Allies and enemies will reveal themselves. We must be on our guard and work together to achieve peace. Because if we fail, then we are facing an extinction-level event. This may be my final broadcast. Good luck to us all.”
In the video, a conduit from the Thames to Empress Hall is constructed, leading to a tank where the Aquakind representatives are to meet with representatives from multiple nations. Aquakind vary in anatomy, some having tails akin to mermaids. Salt exits the tank into the hall.
“If Homo Aqua want a war between the land and the sea, we’ll take the sea,” a bellicose General Oscar Gunsberg (Canadian actor Stewart Alexander) is seen threatening in the video.
Written by Russell T Davies and Pete McTighe and directed by Dylan Holmes Williams, The War Between the Land and the Sea will begin transmission on BBC iPlayer and BBC One in the UK on 7 December 2025. The first episode (43 minutes) will transmit at 8:30pm while the second episode (47 minutes) will follow at 9:15pm BT. The spin-off will transmit exclusively on Disney+ outside of the UK (where available) some time in 2026.