Call the Midwife boss reveals story details about prequel Sisters in Arms with returning characters

This Christmas will look and feel a little different for fans of Call the Midwife. While the main series remains on hiatus, prequel drama Sisters in Arms – set during the Second World War – will make its debut.

The three-part drama follows younger versions of Sister Evangelina, Sister Monica Joan and Sister Julienne – played here by Amy Booth-Steel (Coronation Street, Doctor Who), Helen Schlesinger (Ted Lasso, Albion) and Helena Wilson (The Hills of California, The Custom of the Country), respectively – as they navigate their professional and personal lives during the conflict.

"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," reads the synopsis.

"Together with Sister Alice, and local GP Dr Kit, the nuns dedicate their lives to mothers, babies and the poor. 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 original trio will also be joined by three young secular midwives – Sybil, Olive and Marianne – who "receive a baptism of fire as the blackout and the Blitz take hold".

"While bombs rain from the sky, women give birth underground, families are shattered, children run wild, and whole streets are reduced to rubble," continues the synopsis.

"But courage, compassion and resilience triumph as the community unites in its efforts to survive."

Jenny Agutter, who plays Sister Julienne in Call the Midwife, will narrate the prequel, while Julie Hesmondhalgh (Mr Bates vs the Post Office, Broadchurch) will take on the role of Sister Alice.

Speaking recently to Radio Times at the National Television Awards, where Call the Midwife took home the Returning Drama award, creator Heidi Thomas shed more light on what viewers can expect when they sit down to watch this December.

"It begins with snow, there is fire, there is ice," she teased, describing it as "a really magical revisiting of the popular world", despite the challenging circumstances the characters find themselves in.

"You'll see some familiar buildings... and I really feel as though the new company we've put together is fabulous, and that's partly because they are standing on the shoulders of giants."

Thomas went on to discuss Dr Turner (played in Call the Midwife by her husband, Stephen McGann), who will be depicted in his younger years by Ben Rose (This Town).

"I think he's the image of Steve," she said. "Steve can't see any resemblance, so the audience are going to have to draw their own conclusions."

McGann chimed in: "Do you know what happened? I'm in my house, and when the final casting was confirmed, my good lady wife and my son were conferring, going, 'Oh, he looks like Dad, doesn't he? Doesn't he look like Dad?'"

"He does, he does," laughed Thomas. "But you can't see it, can you, love?"

"I can't see it at all," he added, before talk returned to the plot.

"It's Christmassy," continued Thomas. "It also has quite high stakes. The war really makes its presence felt, not necessarily in the very first episode, but as we go forward.

"So tune in."

Other returning characters include Fred Buckle, who will be played in his younger years by Ciaran Bowling (Dune: Prophecy, Pierre), while Ami Metcalf (Sister Boniface Mysteries, Walking and Talking) will star as his first wife Betty.

Rounding out the cast are Bally Gill (Slow Horses, Interview with a Vampire) as Dr Kit Malhotra, Martin McCann (Blue Lights, Hostage) as Tommy Moffat and Rachel O'Connell (The Young Offenders, EastEnders) as his wife Mary, who will all have their work cut out.

Executive producer Pippa Harris has described it as "thrilling" to watch Thomas create a series that will "delight... the loyal Call the Midwife audience, as well as drawing in new viewers".

"It echoes the original through its blend of engrossing medical stories, wit, and pathos, while the backdrop of WW2 adds a completely fresh layer of tension and jeopardy to the drama," she shared, teasing "a real treat this Christmas".

While Sisters in Arms will debut as a three-part special as part of the BBC's festive schedule, the broadcaster has also confirmed that further details about a full-length series will be announced in due course.

Add Radio Times as a Preferred Source on Google Keep up to date on what’s worth watching with your favourite entertainment news from Radio Times – see more of our exclusive news and interviews featured prominently in Top Stories when using Google.

Add Call the Midwife to your watchlist on the Radio Times: What to Watch app – download now for daily TV recommendations, features and more.

Check out more of our Drama coverage or visit our TV Guide and Streaming Guide to find out what's on. For more TV recommendations and reviews, listen to The Radio Times Podcast.