Call the Midwife viewers are threatening to "riot" if either Sister Julienne or Dr Turner fail to survive the train crash that left them fighting for their lives on Sunday's episode.
Fans were shocked when the characters - played by Jenny Agutter, 69, and Stephen McCann, 59, respectively - were seen lying injured and unconscious as the credits rolled.
They had been returning from a conference when the train they were travelling on collided with another, after the driver suffered what appeared to be a brain haemorrhage.
The popular BBC show's 8 million viewers will have to wait until the series finale on Sunday night to find out if either character survived the crash from the previous episode.
Many fans have now expressed concern for head nun Sister Julienne and Dr Turner - who have been on the show since it's debut in 2012 - following the dramatic scenes.
Linking the disaster to Agutter's role in the Railway Children (1970), fan Anna Madeley said: "I swear if they kill off Sister Julienne in a train crash, who was an actual RAILWAY CHILD, I will not recover. Or Dr Turner for that matter."
Jess Emmerson agreed, commenting: "Honest to god, if anything happens to Sister Julienne or Dr Turner, I'm rioting."
Debbie Skeet said that she hadn't enjoyed it, with her writing: "Call the Midwife is no place for a dramatic train crash. No. Just no. I simply won't allow it."
One viewer called Leah quipped: "Genuinely think that if anything happens to Dr Turner everybody in Poplar will die."
Another fan, Kyla-Shanice, said she would protest if any deaths occured. "If anything happens to Dr Turner or Sister Julienne, BBC, I shall be marching down to you and giving you a very, very stern talking to," she warned.
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Fiona Norris agreed, saying: "I'll be joining you (and, I suspect, a few thousand others!)"
The show's creator and head writer Heidi Thomas, 59 - who is married to McCann - described herself as a "very daring woman" when asked if she would "dare" kill them off.
It's understood that Thomas often ends odd-numbered series with a death - with the upcoming episode set to conclude the eleventh series of Call the Midwife.
A synopsis for the episode states: "Nonnatus House faces its darkest day after a tragic incident in the heart of Poplar. As the community rallies together, the team must overcome personal anguish to help the injured."
Call the Midwife continues on BBC One this Sunday (February 20) at 8pm. You can catch-up via the iPlayer.
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