On the face of it, "Mummy on the Orient Express" is a more traditional Doctor Who story than anything we've seen lately. There's a classic monster (very classic, in fact), a confined space, and a mystery to be solved — but this story manages to turn those ingredients into something totally new. Spoilers ahead...

There's something to be said for a story where the Doctor is not in control of events, and also up against a monster and/or villain that has their own agenda. What's great is that this sort of "trapped and in mortal danger" situation only makes Peter Capaldi's Doctor seem more magisterial and powerful than in the recent stories where he's more or less calling the shots. And it also gives us a new spin on this season's main theme: the new Doctor's apparent callousness, and what it means to be a soldier.

In "Mummy on the Orient Express," the Doctor and Clara go for a jaunt aboard a version of the train that Agatha Christie made famous, except in space. (With Foxes' wonderful jazz cover of Queen's "Don't Stop Me Now.") But the passengers are being murdered by a mummy that only the victim can see, and if you see it then you die 66 seconds later.


The whole thing turns out to be orchestrated by a mysterious figure known as "Gus," who speaks through the train's computer. Gus has arranged for the mummy, known as the Foretold, to be on the train along with a bevy of experts who could possibly capture it. (So "Gus" can replicate it as a weapon.) Once the Doctor rumbles the truth, the train turns into a laboratory. But it's only once the Doctor himself is attacked by the mummy that he figures out its secret, and disables it.

When the story begins, Clara is on her final trip with the Doctor, because she's still pissed at him about his high-handed behavior, especially that time when he forced her to decide whether to kill a ginormous creature hatching out of the Moon. She's decided she doesn't hate him, but she's still fed up with his manipulativeness and brusqueness. She winds up spending a lot of time bonding with Maisie, whose quasi-abusive grandmother was the mummy's first victim, and whose dysfunctional relationship is an odd sort of mirror of Clara and the Doctor's.


But even as Clara starts getting fed up with the Doctor again — he tells her point blank that he can't save Maisie from the mummy, and then reveals that he suspected/hoped that this harmless pleasure jaunt was actually another death-defying adventure — he actually comes through, and is kinder than he appears.

In fact, this time around, the Doctor's callousness has an external cause, because he can't risk "Gus" hearing his plans. The Doctor is able to save Maisie because he pretends he's given up on saving Maisie — his actual plan is to get Maisie into the lab with him, so he can "study" her death, and then take her place. (Presumably, "Gus" would not be in favor of this move because it would risk having the Doctor die too early, when he hasn't yet had a chance to watch several others die and possibly generate useful insights.)


So in a nutshell, this is a story where the Doctor's harshness and apparent disregard for life saves a bunch of people's lives, and it's just a tactic that allows him to save the maximum number of people.

Except not quite.

Because the Doctor pushes it too far — when the mummy "expert" Professor Moorhouse is being attacked by the mummy, Moorhouse is making an effort to report everything he observes about the monster that only he can see. Until the Doctor tells him that any detail he spots might help them save the next person — and then Moorhouse is totally thrown off, realizing that he's already dead in the Doctor's eyes. After that, the Doctor gets nothing more useful out of Moorhouse, who might otherwise have observed the strange markings under the mummy's bandages. So in fact, the Doctor's callous act may prevent him from learning the mummy's secrets sooner, and possibly saving at least Captain Quell.


In any case, this episode puts the Doctor's House M.D.-esque behavior in a new light, by putting him in an impossible situation. As he tells Clara at the end of the episode, sometimes you have no good choices, but you still have to choose. (Whereas last week, he was foisting the choice onto others, because he felt it was humanity's turn to make those tough choices.) When a mummy is picking off people one by one, starting with the weakest — when you've got a gun to your head — you can't afford sentiment, you just have to be bloody-minded.

That's a situation that's pretty much guaranteed to make the Doctor more sympathetic, because if he wallowed in sentiment he'd only be wasting valuable mummy-defeating time. (And in fact, you have to wonder if the Doctor sought out just such a situation, to show Clara why his attitude is sometimes completely warranted.) Clara, who wishes she could quit the Doctor, winds up realizing from Maisie's example that she still has unfinished business with him — and she recasts his heartlessness as a sign of an "addiction" to making those tough choices.


(And then the Doctor turns this on its head, hinting that maybe Clara is also an addict, who's trying — unlike him — to kick her addiction to danger and life-or-death decisions.)

In the end, Clara decides to keep traveling with the Doctor — not surprisingly, since this wasn't a season finale. And it's not just that she feels like he does care, deep down, or that he does make the right choice — she also seems to glimpse some vulnerability in him, when he asks if she would "like to think" that he's secretly a softie, deep down.


Capaldi continues to be incredible in the role of the Doctor. The real joy of this season, thus far, has been watching Capaldi in a variety of situations, just nailing the strangeness and curiosity of the Doctor. I said earlier that he seems at times to be doing a bit of Tom Baker — but his voice is actually reminding me at times of Jon Culshaw doing Tom Baker, instead, in a wonderfully wry tone. He gets so much mileage out of lines like "She was an old woman. It's practically their job description." And of course, "Are you my mummy?"

And meanwhile, Capaldi is constantly using his eyes to telegraph when the Doctor is being especially calculating, or not entirely straightforward with people. In this particular story, especially, the Doctor keeps looking to one side when he talks to Clara, as if he's trying to sneak something past her. The Clara-Doctor relationship has been a lot more fascinating this year, and not just because Clara is no longer a mystery to be solved — both Capaldi and Jenna Coleman are really bringing a lot more layers to their interactions, and it's great to watch. This season's stories, thus far, have ranged from "okay" to "superb," but the performances have been pretty much uniformly great.

Anyway, when Clara changes her mind and decides to keep traveling with the Doctor after all, she uses her boyfriend Danny as an excuse, which is kind of an evil move on her part. She suddenly pretends that it was Danny's idea all along that she stop traveling with the Doctor, and now Danny's changed his mind — and I hope we get to see how Danny reacts when he learns that she's hung him out to dry like that.


Meanwhile, the theme of soldiers also gets moved in a somewhat new direction — this time, it's much more about ex-soldiers who have PTSD and can't escape their past. This is literally true of Captain Quell, who just wants a cushy job on a luxury train and doesn't want to deal with any mummy murders after experiencing the space equivalent of shell shock. And then when the mummy's secret is revealed, the mummy, too, turns out to be an ex-soldier, from a long-forgotten war, who can't die as long as it thinks the war is still going on. (So the secret to disarming it is to say "We surrender.")

So this is a story that manages to cast the ongoing "Doctor's bad attitude" issue in a new light, and also takes preoccupations like "fear of soldiers" and "monsters that mustn't be seen" in new and pretty rewarding directions. "Mummy on the Orient Express" is also a cracking great adventure with a lot of tension and funny bits, both of which benefit from a fast pace and some strong atmosphere.


But we wind up not getting an answer to the biggest question of all: Who is "Gus," and what does "he" want with the mummy's secrets? "Gus" apparently knows who the Doctor is, and is resourceful enough to invite the Doctor onto the train. And the mastermind behind all this is ruthless and prepared to kill a lot of people just to get the Doctor to stop talking on the phone to Clara.

The obvious candidate for "Gus"' identity is Perkins, the super-helpful, charming train engineer who helps the Doctor with his investigation. Perkins seems almost too keen to help, something the Doctor points out once. And he's such an instantly likable, friendly character, you can't help suspecting him. Except that at the end, he gets a look at the inside of the Doctor's TARDIS, and an offer to travel with the Doctor — which he turns down, because he's already seen how the Doctor's lifestyle might change someone for the worse. Is Perkins just playing coy? Does he not want to be too close for the Doctor too long, because he'll get rumbled? Or is he genuinely a decent man who turns down the trip of a lifetime because he fears for his soul?


The other obvious candidate for "Gus"' identity, of course, is one of the people who dies early on — in true Agatha Christie fashion, it's possible Professor Moorhouse, or Captain Quell, or Maisie's grandmother faked their death. Or maybe it's Maisie herself — or possibly, not anybody we met in this episode. In any case, this seems like too big a mystery to be left dangling forever.