In Doctor Who’s olden days, we had cliffhangers. We get them occasionally in New Who as well, but these days we’re more likely to get throw forwards, otherwise known as trailers. How much a throw forward is part of an episode is debatable; sometimes they add little to an otherwise just completed episode. But sometimes they bring something new and interesting to its dying seconds.

Army of Ghosts has a great cliffhanger and an intriguing throw forward. First though, let me witter on about how it gets to those, because this is a smartly structured episode. Writer Russell T Davies has no time to waste, so this week’s alien incursion is already well underway by the time the Doctor (David Tennant, at the end of year one) and Rose (Billie Piper, about to wave the show goodbye) arrive to visit Jackie (Camille Coduri, hooray). They learn about the infestation of ghosts and the Doctor sets about disproving it in a typical “I’m having none of that superstitious nonsense” kind of way.

The quest leads them to Torchwood, much hinted at during this season and about which we’ve been learning about throughout the episode. With the Doctor and Torchwood plot strands combined, Davies splits his story again almost immediately: the Doctor and Jackie discover Torchwood and its role in generating the ghosts, while Rose finds the mysterious sphere and former squeeze Mickey (Noel Clarke). So the stage is set for a two-pronged episode ending.

Meanwhile, Davies has been indulging in a little misdirection. The Doctor assumes that the Sphere is the work of the Cybermen, and Mickey guesses that it contains a big bad Cyber-daddy. The episode is approaching its end when the Cyberleader says they know nothing about the sphere, confounding (hopefully) audience expectations. We end on a double cliffhanger: the Doctor confronted with the prospect of millions of Cybermen around the world, and Rose trapped when a posse of Daleks emerge from the sphere. Fangasms worldwide.

Now for the throw forward, and specifically, its last seconds. Over shots of the Cyberleader, a Dalek and a worried looking Rose and Mickey, we hear a Cyberman saying: “Cybermen plus Daleks. Together we could upgrade the universe”. A tantalising ending, which raises the prospect of something new and nerdy; a match-up between the series two biggest baddies.

Again, its misdirection. No such alliance is forged in Doomsday. One is proposed by the Cybermen and brutally rejected by the Daleks. And of course, when you think about it, that makes sense. As Davies has pointed out, the Daleks are cosmos-conquering, time travelling geniuses. Cybermen are us with bits added. The former has no need for the latter.

But it also reminds us that Cybermen and Daleks are not the same; their technologies might be compatible, but they themselves are not. Davies emphasises that Cybermen are emotionless and Daleks are anything but. They are boastful, quick to anger, goading and they scream inside their bonded polycarbide armour. They can even be tricked into revealing their names by appealing to their pride. Sometimes, even in Doctor Who itself, the Daleks are portrayed as emotionless, rational robots, incapable of imagination and inventiveness. But that’s the Cybermen. Daleks are creatures of pure emotion, specifically hate.

Interestingly, although Doctor Who generally avoids monster match ups (unlike say the 1960s Batman series, which, when ratings were failing, would wheel out a double bill of the Joker and the Penguin, for instance. Zonk!) it often puts supplementary monsters alongside the Daleks to indicate what they are not. They are not, for example, the Robomen, who are brainless slaves. They’re not the Slyther or Varga plants which are simple unthinking beasts. They’re not muscly grunt like the Ogrons or aestheic show ponies like the Movellans. And they’re not Davros, who can hold a (admittedly megalomaniacal) conversation.

So the Daleks are the main game. They outsmart and outgun everybody in order to get their Genesis Ark primed and ready to spew forth millions of themselves in the skies above London. But the Doctor has a trick up his sleeve. He’s worked out that because the Daleks and Cybermen are covered in voidstuff, he can open the breach and they’ll be sucked into it.

Davies can sometimes be accused of employing a quick, convenient solution to his stories; I call it the magic switch. For a classic example, consider New Earth; a cocktail of medicines spreads itself amongst the infected experimentees. Game over, nice and easy. And hey, who can blame him? He’s only got 45 mins an episode, he doesn’t have time to muck around. An ending, albeit one achieved by throwing a magic switch, is still an ending.

But Doomsday does it better. Here the fictional explanation about the voidstuff makes a kind of sense, and is signposted early enough in the episode to make it seem less of an arbitrary quick fix, rolled out as time ticks away. The Doctor’s plan takes time to set up as well; it’s no instant cure all and that also helps sell it to the audience. And it’s not perfect – opening the breach puts the Doctor and Rose at risk too – so it’s hardly convenient. In story terms, it’s no less a magic switch than any other pulled in the series’ long history, but it’s sold to us better.

And so an epic story comes to and end. Daleks and Cybermen thrown into hell, and the Doctor and Rose separated by the walls of parallel universes. And just at the end, we get a surprise; there’s suddenly a bride in control room. Cue the first of our “what? What? What?!” moments. The cliffhanger lives to fight another day.

LINKS to Pyramids of Mars: Torchwood has an Egyptian sarcophagus in it’s collection of stolen alien goods. Surely a hat tip?

NEXT TIME… A space helmet for a cow? It’s back to the Hartnell era for The Time Meddler.