Callie Cooke admitted her 'Doctor Who' episode "has a dark side" despite appearing "shiny and silly".

Callie Cooke has opened up on her Doctor Who debut

Callie Cooke has opened up on her Doctor Who debut

The iconic sci-fi show's latest guest star - who will join the cast for this weekend's episode 'Dot and Bubble' - is playing Lindy Pepper-Bean "an influencer of the future" on the seemingly "carefree" planet of Finetime.

She told the BBC: "The tone of the episode when it starts is incredibly shiny and silly and, to the eye, looks quite harmless.

"But it definitely has a dark side and an undercurrent that is so important, I think [showrunner Russell T Davies] does that so well in his writing.

"And Ncuti [Gatwa] blew us all away on set – he is such a brilliant actor, so you can expect to see that!"

Callie will feature alongside Ncuti's Fifteenth Doctor, and his companion Ruby Sunday, who is played by Millie Gibson.

The episode is also set to include 'White Lines' actor Tom Rhys Harris as Ricky September, and Susan Twist will be back in another new role, this time playing Penny Pepper-Bean.

Callie has "always wanted" to be part of 'Doctor Who', and she's been loving the monsters in the current series.

She revealed: "I’m a Matt Smith fan, also a David Tennant fan because I am obsessed with him as an actor.

"In terms of monsters, I actually think the Bogeyman in Space Babies is one of the scariest monsters I’ve ever seen."

When it comes to her own character, the actress thrived on the challenge of such a "complex" role.

She said: "Lindy is incredibly complex – she’s very privileged, very sheltered, set in her ways, petulant and sometimes a bit annoying – which was an exciting mix to play.

"She really cares about her friends, but she probably cares more about how she looks and comes across more!"