Flatline written by Jamie Mathieson and directed by Douglas MacKinnon

This story in a nutshell: Creatures from another dimension bleed in to ours with devastating consequences...

Indefinable: He's on fire now. There's no mistaking the fact that Peter Capaldi is playing the Doctor and even trapped in the TARDIS in the strangest of circumstances he still manages to steal the show. The crabby old git is delighted at the fact that he has come face to face with something he hasn't expect and doesn't know how to deal with, his shrinking transport. The twelfth Doctor finally gets one of those big brash 'I am the Doctor' speeches but unusually I was cheering rather than trying to gouge my eyeballs out with a rusty fork. It was nice to see him step from the Ship and take his part in the conclusion (this is the opposite of Kill the Moon in that respect where he took part in the main body of the story but stepped out at the end) but more importantly than that I think this was an exclamatory moment where he is established as the Doctor of the moment. He's had moments before in the season where he has flirted with the role but this is where he embraced it head on and stood up for humanity as he has always done. It helps that it was well scripted and played, naturally. Interestingly the Doctor chooses to interpret the two dimensional creatures motives as hostile when he has no real evidence to support that (body snatching could come as natural to them as breathing). I think viewing them as monsters helps to make what he is about to do more comfortable for him. The fact that he chooses to see conflict rather than communication says a lot about this Doctor.

Impossible Girl: Finally Steven Moffat has made his dream come true and excised the Doctor from the show and pushed a companion of his making centre stage. Moffat has a similar obsession with Clara fronting the series as Davies did with Rose and yet I find the on the whole the Doctor managed to keep hold his series in the first four years in a way that Capaldi failed to do so, relenting a little in season eight. The main thrust of the series is the Clara/Danny relationship, Listen saw her taking another important position in the Doctor's history, Kill the Moon left the weight of the climax entirely in her hands whilst the Doctor skipped off for some tea, Flatline writes him onto the sidelines whilst Clara does all the reacting and come the end of the season Jenna Coleman has replaced Capaldi's face on the credits and her name shoots at the audience first in a bizarre gag. Make no mistake - Moffat has gone on record as saying the show is more about the companion than it is the Doctor and certainly this season he has set out to prove it. Strangely I have reached a point in Flatline where I don't mind anymore. Clara is being written for in such a skilful way and Coleman's performance rockets as a result. Seriously, go back and watch her struggling with the insubstantial characterisation she was handed  in series seven and then watch Flatline. There is a massive difference. I don't know if it is confidence, growth or simply that the writing is geared to making her a character who struggles as opposed to a character who smugly takes everything in her stride. It has taken a whole season (Kill the Moon is where I really felt the shift in her character) but finally Clara works and what's more she's likable, practical and relatable. Credit where it is due, that is quite a transition. Flatline shows you how the show can be fronted by a companion and it can still be recognisably great Doctor Who (the only other time I have felt that was Turn Left, which this episode can't quite match).

I still don't like the idea of Clara popping back and forth between two lives - despite the evidence I fail to see how that could work for either parties or be an entirely satisfying existence for her either. It makes me feel like she is only a temporary companion rather than somebody who is embracing the life and staying for good (I know no companion is ever going to stay for good but I do like the illusion that they will be travelling with him indefinitely for some time). She's bequeathed the screwdriver and the psychic paper and I think (given how abusive he has been to her this year) she has more than earned the chance to prove herself. I'd say she's also earned the opportunity to poke fun at the Doctor whilst pretending to be him. She skips away from a harrowingly dangerous experience whilst lilting 'I love you!' to Danny. I've lamented about her fearlessness in the past but this was pulled off brilliantly. She's been lying to Danny about travelling on board the TARDIS and the Doctor wants answers about that. Clara gets some shocking insight into why the Doctor has to make the decisions he does and gets to understand his cold logic a little better. She talks quickly and smartly when it comes to convincing Rigsy not to sacrifice himself at the climax. In a moment of clarity for the character she stops thinking about what the Doctor would do and starts thinking what she is going to do. It's an important moment and the point where the character has outgrown her mentor. A renaissance moment. Clara uses the resources that she has around her (Rigsy's talent, the 2DIS) to think her own way out of danger. The Doctor wont tell Clara to her face that she did an incredible job but when the moment came he was extremely proud of her.

Sparkling Dialogue: 'It's bigger on the inside!' 'You know I don't think that statement has ever been truer.'

'It's long been theorised but no-one could go there and prove its existence without a heck of a diet!'

The Good:

* A beautifully simple teaser that tells you very little about the villain of the piece but informs you that it is going to be something very different to the norm. I love the dreary lighting and uncharismatic panic of the man, right from the off Flatline is aiming for a cold realism.

* I commented in my piece on Listen that horror is far more frightening when you don't know what is frightening the characters. Despite something of an outcry at the indefinite conclusion of Moffat's best episode of the year, I stand by that opinion. A shadow moving, a noise in the next room, heavy breathing behind you, something brushing past you in the dark...scary ideas that would lose their impact if the lights came on and you could see the nasty that you are facing. Imagination takes you much further than prosthetics and CGI. Flatline takes the idea of an unknowable horror and puts a fascinating spin on it - the horror from another dimension is so different from us we can't tell whether their terminal attacks are intentional or simply their attempts to communicate with us. That's a terrifying notion, especially when you could have the dimensions sucked out of you and wind up a silhouette on the wall in the effort to determine their intentions. At the end of the story we still don't know whether this is a spectacularly bad introduction between the human race and the two dimensional beings or whether they deliberately leaked into our plan of existence to wipe us out. The various ways in which the creatures attempt to understand us prove to be far more chilling than any bog standard Doctor Who monster dribbling along a corridor. There is enough of a hint (the chilling moment where they try and communicate verbally and we realise they are targeting the numbers on the workers jackets) that they are doing something by design...but it is never confirmed what.

* I was starting to wonder with a sense of dread that I had seen everything that this show had to offer (at least under a Moffat administration). At the beginning of the season everything was starting to feel a little samey (the Paternoster Gang, another take on the droids from The Girl in the Fireplace, a lone Dalek in a cell, a celebrity historical, the Doctor living the life of a human being for a spell, etc) but somewhere along the line the innovation train took over and fresh ideas have started to emerge. Imagine my delight with Flatline and it's shrinking TARDIS, an idea so simple (and low budget) that I'm surprised nobody (aside from Christopher H. Bidmead before he officially fell in love with the TARDIS and married one) has played about with it before. A toy sized TARDIS with the Doctor inside? A genius notion that kids can mimic with their toys. The rapidly shrinking doors offering some wonderfully odd visuals and comic moments. Matheson doesn't just suggest the idea, he really plays about with it to see how many ways he can delight us. The 2DIS. Come on, a weapon that bring a two dimensional drawing to life and flatten a three dimensional object into an outline? That's bloody cool. 

* 'No decent characters....bibble bibble bibble' That's pretty much been my biggest complaint in Moffat Who and I've started to sound like a broken record. To be honest the characters in Flatline aren't much cop either, which is a shame after Matheson provided a stellar guest cast in Mummy on the Orient Express. What saves this is the performances, the fact that the situation they are placed in is so interesting and that they are true to themselves throughout. Fenton might be a one-dimensional bully that enjoys getting in the way and insulting people but nothing that he goes through in this episode changes that one jot. Rigsy (an unfortunate name that left me thinking about Rising Damp) is Clara's one-shot companion and he's likable enough. You can't help but cheer for the underdog and clearly society has treated this lad badly. I think the problem with the characters in Flatline is that that the setting is looking to be as naturalistic as possible and as a result the cast are all folks you could meet on the street without any particular quirks that make them stand out.

* I can't remember the last episode that conjured up as much dazzling and terrorizing imagery as Flatline; the one dimensional victims trapped in the walls slowly coming to life, the teeny weeny TARDIS with Capaldi's grumpy face peering out, the spatial dimension trickery of seeing the Doctor in the TARDIS being held by Clara (I kept doing a double take), the blistered desert crags adoring the wall that turn out to be a blown up piece of human skin, the fluidic effect of the creatures running across the floor to reach out to the police officer and watching her melt away into the carpet (a million times more effective than a similar scene in Night Terrors), the giant hand that snatches its victim away, the flickering, screaming shadows emerging from the tunnel...

* Why on Earth is there a chair hanging from the ceiling? That was my first question. Where can I get one? That was my second. What followed was one of my favourite set pieces to have sprung from the last four series of Doctor Who. When the couch bursts and melted away like paint simultaneously exploding outwards and inwards I was slack-jawed and had no idea what was going on. That's an exciting feeling I haven't felt for ages. Terrifying in it's strangeness, whacky in design and an amusing cameo by Danny (let joy be uncontained, he can be funny)...I was in seventh heaven watching this on transmission. That would go down as my favourite scene of the year if it wasn't for the TARDIS on the train track (the Doctor on the train track - Uncle Terrance must be appalled!). Walking the TARDIS off the track with his hand and his little dance when he has succeeded left me applauding the TV. I haven't been this much in love with the show for a long time. The build up to the TARDIS being smacked by the train was expertly handled by the director, leaving me breathless.

* One aspect of the show that I cannot fault this year is the music. There have been some repetitive cues but that doesn't matter one iota because they are all fantastic. Flatline has a terrific soundtrack that allows for quiet moments of understated horror as the reality of the danger that the characters face sinks in and also fast moving action, foot tapping cues that me dancing in my seat whilst gripping the arms in fear.

* Trains! Just when you think this is going to be the super cheapie of the season (comparisons with Fear Her were fair, at least in budgetary terms, until about halfway through) Clara and her chums head into the train dock into what proves to be a vast and robust setting. There are no concessions to this being science fiction as far as the setting is concerned, it's forbidding realism all the way. A neglected council estate, the filthy, forgotten storage area of a train station and dark and dank tunnels underground. After reading Damaged Goods this is was precisely the sort of urban realism that I expected Russell T Davies to bring to the show.

* In a season that has thrown all kinds of horrors at us - hands grabbing from under the bed, giant spiders spitting in the face, a desiccated mummy reaching out of its victims - Flatline delivers the most frightening visuals of the year. Ambling forwards awkwardly like Walking Dead rejects with features that melt and cohere endlessly, the two dimensional beings cloaked in human flesh are a chilling sight to behold. No way to reason with them, no way to stop them. They're coming out of the dark and they're coming for you for goodness only knows what purpose. They're relentless, even after Clara has deployed the train. That's enough to give me nightmares. It's their indefinable nature in conception and realisation that chills the blood.

* Even the climax isn't a cheat. Another of my regular complaints is that the conclusion so often fails to match up to what has gone before it. Unanswered questions, bad logic, deus ex machina, spectacle over intelligence...there are a wealth of reasons why so many NuWho adventures don't quite click. Flatline works because it makes up its own rules and it uses them to provide the solution. The creatures trying to open a door that never existed and leeching the power back into the TARDIS (when it was drawn from it in the first place) makes perfect sense. It's very cleverly done.

The Bad: I am reliably informed by a very handsome friend of mine that despite the odd gesture to suggest that this story is set in Bristol that it does not recognise any part of it that he knows (and he should know, he works at the Caaaaan-cel). It's not a problem for me, Doctor Who often dresses up parts of Wales as other parts of the globe but I wonder if it would be different if it were my home town that was being misrepresented? The closest we've come is Brighton in The Sound of Drums and that nearly brought me out in hives.

Result: The series eight episode that single handedly restored my faith in Doctor Who. Kill the Moon was bold and uncompromisingly frightening and daft and Mummy on the Orient Express provided an atmospheric thrill ride but Flatline truly went where Doctor Who has never gone before and I was all of a tingle throughout. I haven't felt this kind of excitement from the show simply through the possibilities of the ideas and the breadth of the storytelling since series four. Flatline is Doctor Who being made for adults with very little in the way of light relief, pleasant characters or quirky settings and it has a truly foreboding menace. How this aired in the same season of The Caretaker baffles me. You wouldn't want the show to be like this every week but my word has it pulled its socks up and delivered something unique and transfixing. What I loved about this story was how it never stopped giving; it opened up in an unique approach (the shrinking TARDIS) and rather than rest on that idea it kept delivering surprising and ingenious notions until my brain was rattling with them. Matheson pins them to a gripping narrative that puts Clara centre stage and truly allows her to shine. Goodness knows where MacKinnon has been hiding these talents but he is making huge leaps in quality with each episode he directs (check out the progress: The Sontaran Stratagem/The Poison Sky, The Power of Three, Cold War, Listen, Time Heist, Flatline). This is the most tautly directed piece of drama to have leapt from Moffat's era, packed full of memorable images and with a tangible sense of tension. I've not been discreet when it comes to my dissatisfaction with the series over the past couple of years and I will equally effusive in my praise for a season that has just knocked three standout episodes out of the park, each one improving on the last. Flatline is bold, imaginative, terrifying and original. An argument for a season comprised entirely of new writers has been made. This is the evidence: 9/10