As we approach the halfway marker of Series 10, it's clear we've had a very strong season so far, but it's a point where we start to wonder how long the momentum can last. With the return of Missy, and an episode written by Steven Moffat, however, you may just have to wait a little longer as this series continues to deliver with Extremis.

From the off, Moffat is on fine form; the episode starts 'A long time ago' as we spiral in on an unknown planet that specialises in executions. To name either the executioner or the condemned would be giving too much away, but typical of Moffat's style, this little narrative which fades in and out of the main story is a pleasant distraction, and you keep wanting to know its resolution.



Ok..we can hear you asking... and YES - we do get to find out who or what is inside the vault, but as we read our checklist of what we can and can't mention in our preview, alas, the identity is something we cannot reveal - although the more astute among you will have probably guessed by now.



The episode is centred around a book called The Veritas - something that anyone who has read has soon after died. The way in which The Doctor is involved is straight out of a Dan Brown novel. In fact, The Doctor can very easily be compared to Robert Langdon (the central character in Brown's books); a smart man, called in by the Catholic church to solve a chilling mystery at its heart. There are scenes that appear to be straight out of Angels And Demons, and the adventure is all the richer for it. Previewing an episode like this is incredibly difficult without giving anything away, but, as you can expect, there is something much larger going on behind the scenes here, and you'll be left with way more questions before the titles roll.

There are so many elements that pull together to form a truly amazing episode of Doctor Who; you have the central season arc referenced, there are truly, TRULY terrifying villains, some amazing sets and locations and a terrific score that makes the adventure way larger than the sum of its parts. In many ways, Extremis feels more like a movie than it does an episode, and by the time the 48-minute timeframe is up, you are desperate for more. For the second time this season there are echoes of Silence In The Library; helped, in part, that there are several scenes set inside the Vatican library, and the re-emergence of a certain...ahem...diary.



We mentioned a couple of episodes back how the horror element has been ramped this season, something that is reminiscent of the Hinchcliffe years of Doctor Who, and as far as villains go, we think that the hooded monks are quite possibly the most frightening and chilling monsters the show has had to date. The look and feel of the monks, coupled with the way in which they talk will creep you out to the max.



Not sure if it is deliberate, but look out for the familiar melody from the opening bars of Thunderball that repeat themeslves throughout Murray Gold's score for Extremis. The similarities to Bond don't end there either, as there's something very Thomas Newman-esque about it, and at one point near the end, there's another familiar Bond riff. Comparisons aside, Gold's music once again takes centre stage and accompanies the adventure with audible precision.



Extremis, although a slower episode than we're used to this season (which isn't a bad thing), is a wonderful reminder of just how good Steven Moffat is as a writer, and why we've been so lucky to have him at the heart of Doctor Who for the past 7 years. This feels like the beginning of his swan song and he is going out in a blaze of glory. But before all that, The Pyramid At The End Of The World beckons...





5 Things To Look Out For:



1) ”Prydonian Chapter”

2) CERN

3) Shhhh! Spoilers!

4) Someone has the authority to "kick The Doctor's ass"!

5) The return of a location The Doctor last visited in Series 6.

+ 10.6: Extremis airs This Saturday at 7:25pm on BBC One.



[Source: DWO]