The Doctor is in ‘absolute jeopardy’ in new episode Boom

The Doctor will be in danger in Doctor Who's forthcoming episode, Boom, writer Steven Moffat has revealed, as he spoke about his return to the BBC franchise.

At the start of the episode, Ncuti Gatwa's Time Lord will step on a landmine and will be unable to move for the rest of the story whilst he and companion Ruby Sunday (Millie Gibson) try to figure out how to save him and the war-torn planet Kastarion 3. Moffat, who is known for his terrifying tales in the series, has now said he wrote the story in order to add "suspense" to the series.

Describing Boom, Moffat said that he was "putting the Doctor in absolute jeopardy", adding that viewers can expect "tension, emotion and the Doctor afraid" over the course of the episode. "The Doctor is not in control of the situation and he cannot do anything," Moffat said.

"He can’t help people, he can’t shove his way to the front and flourish his screwdriver and make something go away. He can do nothing as he can’t move."

Boom is inspired by an episode Moffat liked from the Classic Who era, Genesis of the Daleks, where Tom Baker's Fourth Doctor steps on a landmine on the planet Skaro. Moffat was keen to explore this concert for a whole episode, though at first he was unsure about how he'd return because he'd written so much before both before and during his tenure as showrunner.

Read more: Steven Moffat's scariest Doctor Who episodes

"I was curious and surprised to see that Russell [T Davies] was going back, so I ended up chatting to him. He was sending me stuff about what he was doing, just in a friendly way," Moffat reflected.

Watch the trailer for Boom:

"He kept saying 'Do you want to do one?', and I kept trying to think 'what have I not done?'. I’ve done everything I could possibly think of on Doctor Who. But it occurred to me that Doctor Who doesn’t often do suspense or tension — it does adventure, love stories and comedy all the time.

"It does just about everything, but not a lot of suspense. The Doctor kills suspense because he's funny and in control, which quickly ends any suspense."

Moffat went on to say of his episode: "The Doctor on a knife’s edge, one wrong move and it’s all over. It would take so much away from him — he can’t run about, he can’t bamboozle people and he literally can’t move. I thought 'that’s something that I haven’t done'."

It took Moffat some time before he felt the story was right though, as he explained that he first began writing the script two and a half years ago before ditching it because he felt he had "got it completely wrong", and had "started the story in the wrong place, on the wrong foot".

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"I don’t think I had even told the production office that I had started writing," he went on. "So when I sent it to just Russell he was quite surprised - he didn’t know I had been working on it.

"Mainly, it felt pretty good and pretty familiar to be back on the TARDIS. It doesn’t seem that long ago since I was writing for Capaldi."

New episodes of Doctor Who premiere on BBC iPlayer at midnight every Saturday, and Boom will air on BBC One at 6.50pm on Saturday, 18 May.