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.

With the Doctor and Clara fully back together again after their brief ‘break-up’, it’s time for a small scale invasion of Earth. The duo mistakenly arrive in present day Bristol (or at least good old Wales standing in for it) but it’s not long before the Doctor finds himself trapped in a shrinking TARDIS, while Clara and an unlikely community service gang end up fending off ‘killer graffiti’.

Writer Jamie Mathieson returns for his second and last story of Series 8 just a week after the warmly received “Mummy on the Orient Express”. Although some of the ideas may sound a little like the hugely slated “Fear Her,” there is no need to worry. This is another strong episode with some clever concepts running through it. Hopefully Mathieson will be invited back for more in future.

It seems as though Mathieson may have a penchant for creating creepy and clever monsters. Early on the interdimensional beings here feel very Moffat, it’s a foe that unnerves you because you can’t quite be sure if they are there or not. Is that just a picture on the wall, or is it hiding something more sinister? Like the Foretold, the enemies are nicely realised and brought to life with some impressive CG, particularly once they have ‘evolved’.

A number of fans have been quick to coin this episode the ‘Doctor-lite’, but it’s not really one in the sense that the Doctor is totally out of action. While he does spend almost all of his time stuck in the TARDIS, he’s still there giving Clara advice or rather barking orders at her through an earpiece. Think more along the lines of “The Girl Who Waited”, rather than “Blink”. The Doctor feels present throughout the story even if he’s not there in person.

Clara’s increased attention this year seems to have drawn mixed reactions, some feeling the show has become more like “Clara Who” and not focussing enough on Capaldi’s Doctor. Intentionally or not this episode taps right into that with Clara, armed with the sonic screwdriver and psychic paper, trying out living in the shoes of the Time Lord. It’s done in a playful way at first, but Clara quickly learns that being the Doctor is not as easy she might think when lives are at stake. It brings back some of the prevalent themes this year reflecting on the nature of Capaldi’s incarnation.

The aforementioned community service gang make up the guest characters this week. A few of them are little more than disposable but Joivan Wade’s Rigsy is better served. It’s an undemanding role but he’s a pleasant addition nonetheless. Christopher Fairbank on the other hand is very unlikable as Fenton, deliberately so, but he fits the part well.

This is a very visually taxing episode that plays with both perception and scale throughout. Fortunately director Douglas Mackinnon, returning for his third and final episode this year, proves more than capable of meeting the challenge once again. While a few of the shrink effects may be a bit hit and miss, it’s generally well done.

After a strong build-up the resolution perhaps comes a bit easy, but overall it’s another good episode of Doctor Who, just on the cusp of being great.

Doctor Who TV Verdict: 8/10