Peter Capaldi’s final series at the helm of the TARDIS (sorry for the reminder!) continues this weekend and it’s third time unlucky for the Doctor and Bill as they find themselves treading on Thin Ice. After you’ve left your mark at the edge of the galaxy lightyears in the future, there’s only one place to go next. Home… the long way round. Get in!

Picking up directly where last week’s episode left off (we see a pattern emerging here…), we rejoin our heroes slap bang in the middle of Regency London where, as expected, not all is as it seems amidst the carnivalesque chaos of a seemingly ordinary frost fair. Or at least, as ordinary as a frost fair can be. As an example, there’s an actual sword swallower among the weird and wonderful festivities, so this episode should definitely come with its own ‘Don’t try this at home’ disclaimer.

It’s the Great Last Frost Fair, to be precise, and the year is 1814. Also as expected, Bill has lots of questions. And no, it isn’t a parallel world…

The bustling backdrop is beautifully established by first time Who director Bill Anderson, and once again Bill’s wide-eyed wonderment is a joy to behold. As she takes in her snow-covered surroundings, Pearl Mackie gets the chance to show off her effortless talent when, in the flip of a coin (and that analogy will become clear when you see the episode), she struggles to comprehend the moral high ground that has been embedded within her 2,000 year old tutor. Basically, he moves on.

Bill’s character is already so well rounded that it’s easy to forget that this is only her third episode, and as such she is still getting to know her mysterious new friend. You don’t even realise – or care – that we’re revisiting aspects of the Doctor’s temperament that have been explored before, such as his apparent emotionless reaction to death, as the story allows it to be portrayed in a fresh and interesting way. Combine that with Bill’s unique perspective and it’s further evidence – not that any was needed – that our new TARDIS duo are a match made in televisual heaven.

Bill doesn’t sugarcoat her feelings, and that’s one of the things we love about her the most. Despite the fact she’s centuries away from the world that she knows, this plucky present day gal fits right in, which is partly thanks to the TARDIS’ ever expansive wardrobe. As they step into the story, the escalating drama evolves around them and it doesn’t take long for their fun at the fair to transpire into inevitable anarchy when a young boy’s tragic encounter with a Thames-dwelling serpent sends them on a mission to discover what really lies beneath. There’s definitely something fishy going on and whatever you do, don’t follow the lights…

Children play a big part in this episode, as the Doctor and Bill enlist the help of a band of pickpocketing street urchins who wouldn’t look out of place alongside the Artful Dodger himself. In fact, we expected him to pop up at any moment, and stranger things certainly happen in this madcap 44 minutes. Although the situation is looking increasingly dire, the impressive young ensemble bring some much needed comic relief to the proceedings, particularly when the Doctor, as he puts it, “gets down with the kids”, much to Bill’s hilarious horror. Even her hair is left cringing.

Back to the matter at hand, though, and their investigation soon leads them to the sinister Sutcliffe (right), as played by this week’s leading guest star Nicholas Burns, who is such an indescribably disgusting human being that, when the Doctor does something completely out of character, you can’t help but cheer along. Kudos to Nicholas Burns, who is largely known for his comedic performances, for bringing to life such a skin-crawling adversary. Needless to say, His Lordship’s motivations are truly terrifying.

Of course, it all comes down to Sarah Dollard’s script. The last time she contributed to the show, she broke our Whovian hearts into pieces by killing off Clara Oswald (we’re still not over it), and this time she takes us back to a London that’s just as unfamiliar as Face the Raven’s trap streets, yet instantly as rich and magical. Even if the Doctor never does find out the secret behind that card trick…

One of the most exciting things to take away from Thin Ice is that there’s still so much of the Doctor and Bill to come. As a standalone story, it ticks all the boxes of a classic Doctor Who adventure. It’s set in the past, there’s an alien creature hidden just out of sight, there’s an awesome underwater sequence and, perhaps most importantly, its poignant resolution will leave you shaking your head in disgust and contempt at the human race. It’s like The Beast Below all over again, but the Doctor does get to wear a top hat so you know, swings and roundabouts.

Oh, and you’ll also no doubt be pleased to hear that Nardole makes another all too brief but memorable appearance, as the elusive Vault mystery deepens. And when we say that Thin Ice ends with a “knock knock”, we’re not just talking about Episode 4…