Doctor Who: Heaven Sent

"I've finally run out of corridors..."

Wow. One one level this is a cross between Cube and Blink, but it's a fascinating thing to do with the penultimate episode. Structurally this is just treading water until the finale but the reality is much more interesting than that. This is Moffat, forever doing the big story arc stuff and the donkey work, getting to do a quirky and unusual episode on his fourth year as showrunner: his Midnight or Turn Left. It's also a tour de force of a performance from Capaldi. Whichever way you look at it, it's bloody good.

What elevates it to the sublime, though, is the twist at the end with the teleporter- although what happened to their being called "transmats" in Doctor Who? Proving my theory that, if you're teleported, you die and are replaced with a copy, untold different Doctors have repeated the same day for billions of years, burning themselves at the end of the day so another Doctor can repeat the cycle. It's a kind of Prometheus myth, and it's genius on all sorts of levels.

At the beginning I was wondering if we were looking at the return of the Vashta Nerada, but there is so much cool stuff here, from the Doctor's nightmare to the shifting rooms of the castle- reminded me of both Cube and Castrovalva- to the revelation that the Doctor left Gallifrey not because he was bored but because he was scared. Best of all is the respect shown to the late Clara: the Doctor spends eons mourning, literally, and her presence is everywhere. Her death matters.

At the end, though, we get a revelation: the infamous Hybrid isn't half-Dalek... it's the Doctor!  Is he half-human after all? What's going on? Whatever, we're in for a showdown under Gallifrey's burnt orange skies...