Jenny Agutter says she's in the dark about storylines for the next series of Call The Midwife.
The actress, who plays Sister Julienne in the hit BBC period drama, admitted she has no idea what's in store for the characters in the forthcoming Christmas special and the fourth series.
"I haven't seen any of the scripts so I really don't know. But I know (creator and writer) Heidi Thomas is a very clever writer - she'll be creating things for the actors that will be about real things, but she will be drawing on different subjects than Jennifer Worth's stories," she said.
"From the nuns that were in that house and the midwives of that period, there are very good things to draw on," she added.
Jenny - who reprises her role as a member of the World Security Council in the film Captain America: The Winter Soldier - hopes that Call The Midwife's creator will continue to tackle serious subjects in the next season.
"The last series was very much involved with issues, particular issues like cystic fibrosis, Down's Syndrome and things at the time that were very hard to deal with," the 61-year-old continued.
"I look forward to seeing what Heidi does when writing this next series."
BBC confirmed that Call The Midwife has been commissioned for a 2014 Christmas special, followed by the fourth series, which will screen in 2015.
Stars such as Miranda Hart, Pam Ferris, Stephen McGann and Helen George are expected to return to their roles for the upcoming episodes.
