Doctor Who's Twelve will head into some dangerous new territory during "Kill the Moon."

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The Doctor (Peter Capaldi) and Clara (Jenna Louise Coleman) will find themselves on a shuttle making a suicide mission to the moon during the Peter Harness-penned episode, and the pair's actions will have lasting repercussions. When Clara looks to Twelve for aid dealing with the corpse and spider infested landscape, the young companion will get quite a shock.

Twelve is about to do something drastic, and viewers may not take kindly to his upcoming choices.

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"I still don't know how people will take it. I'm in this kind of limbo now waiting for people to see it, and I've no idea, really I do not know how it is going to go down," Harness told Doctor Who Magazine (via Doctor Who TV). "I've never seen the Doctor do something like this before..."

Will the Doctor put his friend in danger, or will he make a decision that leaves Clara speechless? Find out more when Doctor Who airs Saturdays on the BBC and BBC America.

Click the video below to see a preview for the series' nest episode, "Time Heist."

Tags: Doctor Who television BBC BBC America