Watch: Trailer for the Doctor Who special Eve of the Daleks
Mandip Gill found the plot of this year's Doctor Who New Year special "quite confusing" due to its time loop concept.
The 33-year-old star has been travelling in the TARDIS for several years now, but she still struggles to get her head around the intricate temporal gymnastics of the show's storylines.
Eve of the Daleks will air on New Year's Day and will see the Doctor (Jodie Whittaker), Yaz (Gill) and Dan (John Bishop) pitted against the Time Lord's most formidable foes.
"We did a lot of running, and it got quite confusing at times," Gill told Doctor Who Magazine, via Digital Spy.
"Being trapped in a time loop, repeating the same scenes as it gets closer and closer to midnight."
Doctor Who showrunner Chris Chibnall described the new episode as a "romantic comedy" set on New Year's Eve.
He said: "It’s got the range of tones, the range of scares, the range of humour, and the range of mystery that you’d want on New Year’s Day.”
Gill said she is "excited" to see the finished product, but confessed she had to keep asking director Annetta Laufer which version of the time loop they were currently filming.
She added: "When you read on paper, it's hard to imagine what it's going to look like. But it was good fun to film.
"It was great having Aisling Bea with us. She's so funny. So funny. We had such a good time. Plus, we get to fight the Daleks again."
Eve of the Daleks marks the beginning of the end for Jodie Whittaker and Chibnall, with the actor and showrunner set to depart at the end of 2022 after two further special episodes.
Chibnall will be replaced by Russell T. Davies, who returns to Doctor Who after shepherding the series' revival in 2005.
Davies stepped aside in 2010, after David Tennant's incarnation of the Doctor regenerated into Matt Smith, and handed the reins to Steven Moffat.
Doctor Who: Eve of the Daleks will air on New Year's Day on BBC One.
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