This Saturday’s episode of Doctor Who will apparently be a real game-changer for the sci-fi series, with head writer and executive producer Steven Moffat describing it as “uncharted territory” for the nearly 54-year-old drama.

“The Doctor has already lost, Earth has already fallen and it hasn’t just happened,” the Scottish screenwriter says in a new promotional video for eighth episode The Lie of the Land (written by Being Human scribe Toby Whithouse).

“It happened six months into a new totalitarian regime with which the Doctor is co-operating.

“We are in completely uncharted territory as we enter this Doctor Who story,” he concludes. Sounds like this could be the biggest challenge the Doctor has faced yet…

Doctor Who continues on BBC1 this Saturday 3rd May at 7:35pm