Note: Doctor Who TV’s pre-air reviews aim to be as detail-free as we reasonably can while still offering a critique, but as everyone’s spoiler sensibilities are different, we advise you read on at your own discretion.

A foreword: Unlike last week, the preview copy Doctor Who TV viewed was complete with no removed scenes (that we know of anyway, the BBC could always pull a surprise). However this doesn’t make reviewing the episode any easier as there’s a laundry list of things that can’t be spoiled before air.

So here we are at the grand Series 8 finale and “Death in Heaven” picks up right where “Dark Water” left off with the Cyber invasion of Earth in full swing. It doesn’t take long for UNIT to turn up and try to contain the situation. The Doctor eventually finds himself on board UNIT’s fancy new Air Force One-esque plane, in a surprising new position. Meanwhile his arch-enemy is waiting to unleash the next stage of her plan.

If you thought last week’s episode was dark, it was just the appetiser. This might prove another slightly controversial episode for its further exploration of grim themes, with plenty of unsettling moments and overall bleak tone. There’s the odd bit of humour, but for a good 75% of the episode it’s about as far away from family friendly drama as Doctor Who is likely to get. It almost feels like Moffat sat there and said, “Right then, you want darkness, death and actual consequence. Well here you go!” Suddenly the fairytale nature of “In the Forest of the Night” is starting to make a lot more sense.

If part one of the story was more focussed on Clara, part two switches things up and gives Peter Capaldi a bit more time to shine. It’s a wise move as it allows the Doctor to interact with his arch-enemy and have a bit of self-reflection in the process. The themes that have been bubbling since he first pondered “Am I a good man?” all come to a head. There’s a couple of brilliant Doctor-y moments from Capaldi and his latter scenes are powerful and bittersweet.

After Missy revealed herself as the Master (and she most definitely is, if there was still any doubt), it’s time for the gloves to come off. Michelle Gomez is very, very scary fully embodying this psychotic Mary Poppins with abandon. There’s a particular moment in the episode when she is so cruel, it will likely cause a bit of heartbreak in the fanbase. Sadly partner in crime Seb is wasted, which is a huge shame after Chris Addison gave us such a memorable character in part one.

While the Cybermen are playing second fiddle to the Master, this finally feels like the story that does the old metal menace justice in the revived era. At least in terms of realising the true nature of them and exploring the body horror that they encompass. There are evidently some similarities to the Rise of the Cybermen two-parter, but that story felt a lot safer.

It’s fair to say that Clara and Danny were in a bit of a pickle at the conclusion of last week’s episode and it’s hard to discuss where the pair end up. All we can say is that both Jenna Coleman and Samuel Anderson deliver some great performances with some particularly challenging material.

Returning are Jemma Redgrave and Ingrid Oliver as UNIT’s Head of Scientific Research Kate Stewart, and her adorably geeky assistant Osgood, respectively. Kate makes sure her father’s legacy is honoured, in quite a surprising way, while Osgood gets an offer she can’t refuse. Joining the UNIT pair is Sanjeev Bhaskar, who adds little to the plot in his minor role as Colonel Ahmed.

Director Rachel Talalay has her work cut out in the concluding episode with more varied locations, visual effects and action sequences (including one straight out of James Bond). Fortunately she delivers on both the action and the quieter moments.

There’s lots more to talk about and fans have a lot of questions going into this one, not just from last week’s episode but Series 8 as a whole. Questions like, was Missy the woman in the shop? Why did Missy say my Clara? Who is Seb really? How did the Master escape Gallifrey? Is the hunt for Gallifrey still on? …The list goes on. A number of these are indeed answered, but there’s some things Moffat is clearly holding back for future.

To conclude then, “Death in Heaven” is a largely satisfying, if bleak, conclusion to the story and Series 8 overall. Happy birthday…

Doctor Who TV Verdict: 9/10