We find the 13th Doctor confused and vague as he gallops across time in his new form. Lodged in a dinosaur's throat, he finds himself in Victorian England, contending with his latest regeneration, in addition to some mechanical villains.
This is a scary time for the Doctor. His face is old and he's been through a lot. The Impossible Girl is there, but is she there for him? And why is she always there?
This issue of the old face becomes central to the new storyline, as does the issue of what kind of person is the Doctor.
There are some classic (or soon to be classic) scenes in this episode. He fights a cyborg and when he holds up a reflection to the machine's half-human face, he also sees his own; he's been transformed and is not sure he likes what he has become.
One wonders if he will betray his companion Clara. He abandons her to the cyborg. In true Doctor fashion, he returns to save her.
In a suspenseful climax, we are forced to wonder if the Doctor is a killer. Or if his enemy is just desperate, dreaming of a promised land, having taken on human delusions after reconstructing himself into half-human form, and so is driven to end it all. In the end, we find no answer, except that maybe one of them is mechanical and the other is not. I know, I'm being as vague as the new Doctor. Spoilers.
We wonder if Clara has as much trouble with the Doctor's old-new face as much as he does. An incredible scene between her and Madame Vastra in which the Impossible Girl is forced to look past the veil that conceals an unwanted face, reveals much about this mysterious girl and gives her substance: Or is it that Clara is finally aware? She is tormented, for sure, by the fact that her Doctor is old, confused and seemingly less caring. We all get old Clara. Nobody lives forever.
Or do they? The Doctor has lived past his 12th and final regeneration and has come out weak and scared. The Doctor calls on Clara to love him enough to see him through this difficult time. The Impossible Girl always has.
Who sends the Impossible Girl? Why is she always there? We are asked this question in this episode and are left hanging. Will we ever find out? Who is the Doctor's girlfriend, and does she have anything to do with it? Another interesting question we are teased with.