With the slogan, “Keep your eyes on the seas…” the BBC has announced that the Doctor Who spin-off, The War Between the Land and the Sea will launch on iPlayer and BBC One in the UK on 7 December 2025.

Episodes 1 and 2 will transmit on 7 December, Episodes 3 and 4 on 14 December, and the final episode on 21 December on BBC One.

The five-part series follows Barclay (Russell Tovey), a low-level UNIT staff member whose ordinary life becomes a world of terror when an ancient species rises from the sea. Barclay becomes humanity’s ambassador when the mysterious Salt (Gugu Mbatha-Raw) emerges from the Tank at a summit on the Thames. UNIT, led by Kate Lethbridge-Stewart (Jemma Redgrave), fights for control as humanity faces destruction.

The series cast also features Ruth Madeley as Shirley Bingham, Alexander Devrient as Colonel Christofer Ibrahim, and Colin McFarlane as General Austin Pierce. Other previously announced cast members include Adrian Lukis, Patrick Baladi, Francesca Corney, Mei Mac, Vincent Franklin, Waleed Hammad, Iestyn Arwel, Hannah Donaldson, Manpreet Bachu, and Ann Akinjirin.

Showrunner, co-writer and executive producer Russell T Davies said: “We’re so proud to launch this show at the height of the schedules – and then all five episodes will combine to make a terrific box set to watch over the Christmas holidays!”

He also said the series will feature war, revenge, betrayal, pearls, submersibles, romance, a treacherous No.10 (UK Prime Minister’s office), and a plastic apocalypse.

The Royal Television Society will host a special The War Between the Land and the Sea screening and panel at Chapter Arts Centre in Cardiff, Wales on 27 November.

Written by Russell T Davies and Pete McTighe and directed by Dylan Holmes Williams, the first two episodes of The War Between the Land and the Sea will transmit on BBC iPlayer and BBC One in the UK on 7 December 2025 at 8:30pm BT. The spin-off will transmit exclusively on Disney+ outside of the UK (where available) some time in 2026.