I love the 1920s-inspired setting of this story, transported into space, it is a wonderful visual. The entire events of the episode unfolding on a train, with a limited number of people aboard, draws brilliantly from Murder on the Orient Express and space travel adds a distinctly sci-fi twist.

Frank Skinner is an excellent addition to the guest cast, and the Mummy is one of the most frightening creatures ever seen in Doctor Who. It’s a huge success, both in terms of its design and the visceral tension it generates.

I could have done with about half as much of the tension between Clara and the Doctor. Capaldi’s Doctor is already dark and complex enough without creating needless barriers to his likability.

That said, this is undoubtedly a strong debut story from Jamie Mathieson. Memorable, innovative, and iconic. Even if the ending wraps up a bit too conveniently, the story’s overall quality and distinctiveness more than make up for it.