Few Doctor Who stories reach the heights of this one. It feels like Steven Moffat returning to his roots, crafting a chamber piece—or rather a series of them—with a small cast of only three. Two characters are explored at different points in their lives, but not the two you’d expect. The story delves deeply into themes of fear, particularly primal childhood fears, while also revealing something rare: a glimpse into the Doctor’s childhood and how it connects to his purpose.

Peter Capaldi’s performance here is exceptional. In this episode, the Twelfth Doctor feels more at ease, no longer needing to emphasise “whether he is a good man”. Instead, he fully inhabits the darker, spookier tone of the story, which suits him perfectly. Despite its serious themes, the episode is interwoven with the charming never ending date between Clara and Danny Pink. Their date night is split up so perfectly with this grand intergalactic adventure, it is handled with elegance.

This episode captures the essence of what Steven Moffat does best. The highest praise I can give is that the episode made me want to rewatch it immediately—even while watching, the urge to revisit it is irresistible. This is undoubtedly the high-water mark of the Peter Capaldi era so far and a brilliant showcase of what his Doctor is capable of.