Call the Midwife will see Poplar turned into a warzone as the nurses and nuns will continue to work from Nonnatus House as the London Blitz takes hold.14:03, 09 Aug 2026Updated 14:09, 09 Aug 2026Call the Midwife is returning with three new unmissable episodes.‌The BBC period drama concluded series 15 earlier this year with an emotional finale set in 1971, which saw the death of Sister Monica Joan (Judy Parfitt) and left the future of Nonnatus House unknown.‌Later this year, Call the Midwife will turn back the clock to World War II as bombs rain down in Poplar, East London, at a time when the National Health Service was non-existent.‌The prequel series, titled Sisters in Arms, is set in 1939 and will see three familiar nuns in the earlier stages of their careers, and be joined by some new faces. Here's everything you need to know about the forthcoming mini-series.What is Sisters in Arms about?The Call the Midwife prequel will consist of three episodes and follows the nurses and nuns from the convent as they battle to support their beloved community in East London as the Second World War breaks out.‌According to the BBC's synopsis: "In September 1939, Sister Monica Joan is in her prime, Sister Julienne and Sister Evangelina are young and zealous, and Nonnatus House is the beating heart of Poplar."Together with Sister Alice, and local GP Dr Kit, the nuns dedicate their lives to mothers, babies and those in need. But there is no gas and air, no penicillin, no cure for TB, and no welfare state. Then war is declared – and life gets even harder.""The three young secular midwives who complete the team – Sybil, Olive and Marianne – receive a baptism of fire as the blackout and the Blitz take hold," continues the synopsis.‌"While bombs rain from the sky, women give birth underground, families are shattered, children run wild, and whole streets are reduced to rubble. But courage, compassion and resilience triumph as the community unites in its efforts to survive."Who is starring in Sisters in Arms?Created, written, and executive produced by Heidi Thomas, Sisters in Arms welcomes a new cast, including Coronation Street's Hayley Cropper star Julie Hesmondhalgh as Sister Alice.‌Theatre star Helena Wilson is taking on the role of a young Sister Julienne, though the original actress, Jenny Agutter, will be narrating the miniseries.Ami Metcalf, who played Lynette in the first Christmas special, is returning as Betty Buckle, the first wife of Fred Buckle, now played by Ciaran Bowling.Here is the cast list for Sisters in Arms:‌Julie Hesmondhalgh as Sister Alice.Helen Schlesinger as Sister Monica JoanAmy Booth-Steel as Sister EvangelinaAmi Metcalf as Betty BuckleCiaran Bowling as Fred BuckleHelena Wilson as Sister JulienneLizzie Back as Sybil MaxtedEllie McKay as Olive DobbsLiv Andrusier as Marianne SieglerBen Rose as Dr. Patrick TurnerBally Gill as GP Dr. KitWhen will Sisters in Arms broadcast?Filming has wrapped on Call the Midwife: Sisters in Arms with Heidi Thomas sharing behind-the-scenes secrets.‌"Call the Midwife has a long and noble history of filming Christmas specials during heatwaves, and this year we welcomed the snow-machine back to the Nonnatus House set like an old friend," she said."But I was surprised how many new emotions Call the Midwife: Sisters in Arms sparked. In particular, the evacuation of Poplar's children, and the fear that they may not make it home for Christmas, had us all in tears."The BBC has confirmed Sisters in Arms will air on BBC One and iPlayer this Christmas, though the exact days and times are yet to be confirmed.Article continues belowCall the Midwife previously aired on Christmas Day 2025 at 8:15pm followed a second sitting on Boxing Day at 8:30pm.Call the Midwife is available to stream on BBC iPlayer