A new crisis from the deep ocean brings together a team of both new faces and familiar favorites from the Doctor Who universe in The War Between the Land and the Sea. This five-part miniseries started on BBC One and BBC iPlayer on December 7, 2025. With the Doctor not around, the job of saving the world falls to UNIT and an unlikely human ambassador who must negotiate with an ancient, angry species known as the Sea Devils, or Homo Aqua.
The show is led by Russell Tovey and Gugu Mbatha-Raw, who both have a history with Doctor Who but are playing completely new characters here. They are joined by several actors reprising their roles from the wider “Whoniverse,” including Jemma Redgrave as the leader of UNIT.
Main Cast and Characters: Who Plays Who
The cast blends a human diplomatic team with the mysterious leaders of the sea-dwelling Homo Aqua.
Russell Tovey plays Barclay Pierre-Dupont
Barclay is not a high-ranking officer or a seasoned diplomat. He is a low-level UNIT employee whose job involves routine tasks like arranging transportation. His life changes when he is unexpectedly chosen to be humanity’s primary ambassador to the Homo Aqua. Actor Russell Tovey is known for shows like Being Human and Years and Years. Doctor Who fans might remember him playing Alonso Frame in the 2007 Christmas special “Voyage of the Damned”.
Gugu Mbatha-Raw plays Salt
Salt is the leader and representative of the Homo Aqua, the species humans call the Sea Devils. She emerges to confront humanity about the damage done to the oceans and forms a key, complex relationship with Barclay during the negotiations. Gugu Mbatha-Raw previously appeared in Doctor Who as Tish Jones. Her other major roles include the Black Mirror episode “San Junipero,” Loki, and The Morning Show. She described the detailed prosthetic makeup required for the role, joking that her co-star’s dog did not recognize her.
“The prosthetics are just so detailed,” Gugu Mbatha-Raw said. “I’d forget I was dressed as Salt, [Russell Tovey’s] dog Rocky would growl and I’d think: ‘Oh yeah, I’m blue’.”
Jemma Redgrave plays Kate Lethbridge-Stewart
Kate Lethbridge-Stewart is the commanding officer of UNIT, a role she has held since her first appearance in Doctor Who in 2012. As the crisis escalates, she is the one who must make the tough strategic decisions to try and prevent a global war. Jemma Redgrave is also known for her roles in Bramwell and Holby City.
Alexander Devrient plays Colonel Christofer Ibrahim
Colonel Ibrahim is a senior security officer within UNIT and part of Kate Lethbridge-Stewart’s core staff. The character first appeared in Doctor Who in 2023. Actor Alexander Devrient has also been in Ted Lasso and The Danish Girl.
Returning Whoniverse Favorites and New Faces
The series features a deep supporting cast that connects it to other stories while introducing new characters.
Ruth Madeley plays Shirley Anne Bingham
Shirley is UNIT’s scientific advisor. She uses her knowledge to analyze the Homo Aqua and understand their biology and motives, which helps shape UNIT’s response. Ruth Madeley first played this character in Doctor Who in 2023.
Colin McFarlane plays General Austin Pierce
General Pierce is a high-ranking American military officer working with UNIT. This marks a notable return for the character and the actor; McFarlane first played General Pierce 16 years ago in the 2009 Doctor Who spin-off Torchwood: Children of Earth. Outside the Whoniverse, McFarlane is known for playing Commissioner Loeb in The Dark Knight films.
Key Supporting Cast Members:
- Adrian Lukis as Jonathan Hynes: A politician who is initially appointed as the human ambassador before being replaced by Barclay.
- Ann Akinjirin as Barbara Pierre-Dupont: Barclay’s estranged wife, with whom he shares a child.
- Francesca Corney as Sergeant Hana Chakri: A UNIT soldier assigned to protect Barclay.
- Vincent Franklin as Harry Shaw: The Prime Minister of the United Kingdom.
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Where to Watch and Episode Schedule
The War Between the Land and the Sea premiered with a double-bill on Sunday, December 7, 2025, on BBC One in the UK. New episodes are released weekly. All episodes are available to stream on BBC iPlayer.
For viewers outside the UK, the series will be available to stream internationally on Disney+ in 2026. An exact release date for Disney+ has not been announced.
Below is the release schedule for the five-episode series:
| Ep. | Episode Title | UK Release Date (on BBC iPlayer) |
|---|---|---|
| 1 | “Homo Aqua” | December 7, 2025 |
| 2 | “Plastic Apocalypse” | December 7, 2025 |
| 3 | “The Deep” | December 14, 2025 |
| 4 | “The Witch of the Waterfall” | December 14, 2025 |
| 5 | “The End of the War” | December 21, 2025 |
Behind the Scenes of the Series
The series was created and written by Russell T Davies, the current showrunner of Doctor Who, who also co-wrote the series with Pete McTighe. All five episodes were directed by Dylan Holmes Williams. The music is composed by Lorne Balfe, whose soundtrack album was released in December 2025.
The story is set firmly within the Doctor Who universe but is designed to be a standalone watch that doesn’t require prior knowledge of the series. Davies described the show as focusing on the emotional core between the two lead characters, Barclay and Salt.
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