Doctor Who icon reveals shock PTSD diagnosis in surprise return to BBC show

Ruby Sunday is back - but she’s not the same girl who once ran wide-eyed through space alongside the fifteenth Doctor played by . Former actress reprises her role in ’s fourth episode, Lucky Day, and teases a more grounded Ruby.

“You see more of a mature and stronger version of her,” she says. “She’s trying to pretend everything’s back to normal, but she’s still processing it all.” Despite appearances, Ruby struggles to cope but brushes her struggles under the rug. However, emotions reach a high in the when her past and present collide.

READ MORE:

But she finds solace in newcomer Conrad, played by star . “She opens up to Conrad about her from her travels,” Millie says, “It’s a really strong scene."

Jonah was delighted to share the spotlight with Millie. “We had so much fun,” he says, “We were on set together all day every day for weeks.”

More than a job, entering the Whoniverse was a dream fulfilled for Jonah. “I’ve been a big fan of Russell T. Davies’ work for years,” he says.

But the real highlight? Meeting the fifteenth Doctor himself. “Ncuti Gatwa is every bit as charismatic as you’d expect,” Jonah says, “It was the first time we worked together.”

Though still haunted by the trauma of her travels, Ruby slowly rebuilds her life after leaving the fifteenth Doctor last season. A major turning point? Joining UNIT, the Earth’s frontline defence against alien threats.

There, she finds a much-needed support system. “I absolutely love working with and ,” Millie says, referring to their returns as scientists Kate and Shirley. “They’re like Ruby’s third and fourth mums.”

Millie and Ruth bonded over shared roots - years after her exit from Corrie, the actress, 20, was happy to reminisce about her time in Manchester with the Westhoughton native. “Ruth lives in Manchester,” Millie says, “When we met, we were like, ‘Oh, you’ve been to this pub.’ That was great!"

But while she tries to move on, the Shreek - a terrifying new monster - looms over the episode, just as her romance with Conrad blossoms. But Conrad’s no ordinary love interest.

He shares a mysterious link to the Doctor. “He met him as a child and became obsessed,” Jonah says, “He’s a superfan. He’s desperate to meet him.” That fixation sparks unexpected tension. “It’s like when your new boyfriend wants to outshine your ex,” Millie says.

With monsters, mystery and emotional growth, Lucky Day promises to be a character-defining moment for Ruby - and a must-watch for fans.

Like this story? For more of the latest showbiz news and gossip, follow Mirror Celebs on , , , , , and .