Call the Midwife star Laura Main has teased a cliffhanger involving a "much-loved" character at the end of part one of the Christmas special.
The actress, who plays Shelagh Turner in the BBC period drama, appeared on BBC Breakfast on Tuesday morning and said fans will be "wanting to tune in again" after the end of the first 60-minute episode.
When quizzed by host Sally Nugent about the cliffhanger, Laura didn't give much away. "Yes. It does involve a much-loved member of the community so yeah, you'll be wanting to tune in again," she said.
As a photo from the special flashed up on the screen, showing the nurses and midwives singing carols outside Nonnatus House, Laura continued: "That image of us singing carols, I think that comes to… Oh, I'm giving away too many secrets now but you get all the rousing finishes, the Christmas magic as well in each episode," she said, adding: "You'll be filled up by it I think."
So, what can fans expect from the upcoming special?
When we return to Poplar, the year is 1969 and the Nonnatus midwives are busy doing what they do best: delivering babies!
Meanwhile, the funfair has come to town, bringing some excitement and colour to the borough – but there are some much less cheerful visitors too, including influenza and the Hong Kong flu.
Elsewhere, as rehearsals for a carol concert get underway, Poplar is rocked by the news of an escaped prisoner and after a spate of break-ins, residents begin to fear that he may be in the local area.
The synopsis continues: "The Turner children are caught up in the fever surrounding the Blue Peter Christmas appeal to collect dinky cars and scrap metal. Trixie makes a fleeting visit to Nonnatus House and is delighted to see her brother Geoffrey, and Miss Higgins has her grandson Harry stay for Christmas. Violet hosts a mince pie competition but the Buckles' preparations for Reggie's homecoming are thrown into turmoil."
Expanding on Reggie's storyline, Cliff Parisi, who plays Fred Buckle, said that "things get out of control" for his on-screen son.
"He's now becoming a young man, and they're trying to respect that and trying to make him more responsible," he told RadioTimes.com. "On this particular occasion, things get out of control. I think it does remind them how vulnerable he can be."
He added: "Things are all right when they go right, but if they go wrong, he doesn't have another option. He doesn't know what to do."
Helen George, who plays Trixie, also revealed what fans can expect from her character, who decided to join her husband Matthew in New York at the end of series 13.
Speaking in a behind-the-scenes video posted on the show's official Instagram page, Helen said: "I think what's great is Trixie, she's gone to New York and started a life out there but can't wait to get back to Poplar and back with her family for Christmas."
The Call the Midwife Christmas special airs on BBC One on Christmas Day at 8pm. Part two will air Boxing Day at 7:30pm on BBC One and iPlayer.