Oooh, a two-parter, so here goes with what’s probably going to be a long report…
While the Doctor is away teaching Donna how to drive the Tardis, something a wee bit odd is going on back on earth. Cars are being fitted with remarkable devices that clean up all polluting emissions, and that include a slightly over-enthusiastic satnav. We’ve all heard the stories of drivers following the instructions a bit too literally and driving into rivers, but Atmos goes one step further. If you don’t follow its directions, it’ll lock the doors and drive you into the river anyway. A journalist investigating the system is killed in this manner after being thrown out of the slightly creepy Rattigan Academy by its founder, alienated young genius Luke Rattigan, who doesn’t seem at all interested in her suggestion that Atmos is dangerous. Fortunately, she managed to leave a message for UNIT before dying. When it transpires that a lot of people all over the world have died in the same way at the same time, it’s time for UNIT operative Martha Jones to call a Time Lord. Sorry, I was just trying to say “time” a lot in that sentence. It seemed like a good idea at the, err, time. Anyway, Martha calls the Doctor on the phone she gave him at the end of Last of the Time Lords, and so the Doctor and Donna return to present-day Earth.
And they arrive just in time for UNIT to raid the Atmos factory. There’s lots of fun with reviving UNIT – the Doctor always had an uneasy relationship with the military, and these days, what with Time Wars, and all the other fun, he’s even less keen on people waving guns around. But he settles down to work with Colonel Mace, whose troops search the building. Down in the basement, two soldiers find a couple of goons guarding a door, behind which they find something very nasty in a vat of green goo – somebody seems to be growing a human body. But before they can do anything about that, they meet something even nastier: General Staal, a more or less typical Sontaran (nasty, brutish and short…). After a brief discussion involving zapping, pain and mental conditioning, the soldiers become zombified agents of the Sontarans. Now that can’t be a good thing.
Meanwhile, as the Doctor, Martha and the rest of UNIT try to work out what’s going on, Donna turns up something very interesting. None of the factory workers have ever had a sick day. Not one. While Martha investigates this, Donna goes to see her family and the Doctor goes to have a word with Luke Rattigan. He’s driven there by Ross Jenkins, an young UNIT soldier.
Luke’s a bright boy, but he’s a little warped. He’s got lots of interesting toys, but the Doctor is pretty sure that he shouldn’t actually have that teleport pod. He’s even more sure that a Sontaran shouldn’t be coming out of it, and decides that being somewhere else might be a good idea. In a repeat of his satsuma trick, he throws a squash ball so that it bounces in just the right way to thump the Sontaran’s probic vent, that
convenient plot device critical weakness that encourages the cloned warrior race to always face their enemies. After a quick burst of sonic screwdrivery to block the teleport, he runs off with Ross. Of course, that doesn’t go too well, as the UNIT Land Rover is fitted with an Atmos unit, which attempts to kill the Doctor in the same way as it did the journalist. He manages to confuse its poor little brain and he and Ross escape. The Atmos unit blows itself up. Rattigan and his Sontaran pals believe that the Doctor is safely dead, of course.
Meanwhile, back at the factory, Martha runs into a bit of trouble when she’s taken to the basement by the zombified soldiers. The Sontarans turn their clone template thingy from the vat into a duplicate of Martha, and wire Martha up to some fancy kit that feeds her memories into the clone. The clone takes Martha’s place, and that causes a bit of a problem when the Doctor calls her and asks her to tell Colonel Mace that he has a Sontaran problem. She doesn’t.
The Doctor goes to collect Donna, and that’s when the Sontarans decide to bring their operation forward. Rather than wait for all 800 million cars to be fitted with Atmos, they’ll start things up now with just 400 million fitted around the world. Cars start spilling out thick, choking fumes. They also do fun things like locking people in their cars, which is a little inconvenient for Donna’s grandfather Wilf. Meanwhile, Rattigan is doing some male bonding with the Sontarans, who’ve got a nice little Sontar – ha! chant routine.
And that was a nice point to end the first part. All very strange. What are the Sontarans up to? They’re supposed to be direct all-action warriors, so poisoning people seems a bit out of character…
All over the world, Atmos units are uncontrollably spilling out fumes. While UNIT struggle to deal with the situation, Clone Martha downloads their control systems into her PDA. And while that’s going on, those zombified soldiers attach some devices to the Tardis which is promptly transported to the Sontaran ship. This is a little incovenient for Donna, as she’s in it.
Rattigan, feeling all excited, tells the Sontarans that he’s going to gather his own troops, and teleports back to his Academy. His students turn out to be not at all keen on his plan to migrate to a new world that his “friends” have located for him. They all run off, in fact.
While the exact nature of the Atmos gas hasn’t been worked out, one thing is clear: once it gets to 80% concentration, it’s lethal. And it’s getting thicker by the minute..
Despite the Doctor’s warnings, UNIT plan a coordinated nuclear attack on the Sontaran ship. While this probably wouldn’t have been all that effective anyway, Clone Martha uses her PDA to stop the launches. And it’s at more or less that point that the Sontarans attack – their aim is to protect their asset – that would be Clone Martha. Or possibly Real Martha, as Clone Martha depends on a feed from her. As the Sontarans have fancy stuff that makes bullets expand so they jam guns, the UNIT soldiers don’t do too well in the fight.
Rattigan pops back to see his potato-headed friends, and apologises for not being able to bring his troops. The Sontarans aren’t that bothered, as they were only going to use them for target practice anyway. Yes, the new world Rattigan had been promised turns out to be a hoax. They just used him to get the Atmos devices installed. And err, they don’t really need him any more. He just manages to teleport home before he can be shot.
UNIT have another plan. After issuing all their people, including the Doctor with gas masks – the Doctor can’t resist saying “Are you my Mummy?”, of course. Then the Valiant arrives, uses its engines to clear the fog then its energy weapons to clear some Sontarans. UNIT troops with slightly better weapons go on the attack, and remove even more Sontarans.
The Doctor, who’s been giving Clone Martha some odd looks, especially after she admits not having called Real Martha’s family to warn them about the little matter of the toxic fumes, takes her down to the basement, where he finds Real Martha and disconnects her from the Sontaran equipment. Clone Martha promptly collapses, but stays alive long enough for Real Martha to get her to reveal the content of the gas. Its secret ingredient is Sontaran clone food. They don’t want to conquer Earth, they want to use it as a base for growing more Sontaran clones for their long running war with the Rutans.
The Doctor calls Donna to get her to reactivate the teleport system so he can bring both her and the Tardis home. After bashing a probic vent with a hammer, she manages to do just that. He then goes back to Rattigan’s place, where he finds just the thing he needs – an atmospheric converter, which Rattigan would have used for sorting out the atmosphere on his new world. He tweaks it a bit, and sets it off. Fire rolls through the atmosphere, burning away all of the Sontaran gas. The Sontarans are a bit annoyed about this, and prepare for an actual, more tradition.
Bidding farewell to Donna and Martha, and telling Rattigan to do something smart with his life, the Doctor teleports to the Sontaran ship with the atmospheric converter. If it goes off, it will destroy the ship. Being the Doctor, he can’t just send it up there – he has to give them the chance to leave. Being Sontarans, they refuse the opportunity. Rattigan manages to do something smart, and twiddles with the teleport, so that the Doctor comes back to Earth, and he takes his place. With a quick “Sontar – ha”, he presses the button and the Sontaran ship is quite spectacularly destroyed.
With all that sorted out nicely, the Doctor, Donna and Martha are together in the Tardis. Martha confirms her decision to stay on Earth where she’s needed, but just as she’s about to leave, the door slams shut and the Tardis takes off. And the Doctor isn’t driving.
Somebody obviously wants to see the Doctor. Next week’s episode is called The Doctor’s Daughter, which sounds interesting. When we first met the Doctor in 1963, he was travelling with Susan, a young woman who was introduced as his granddaughter. And a while ago, he did say that he was a dad once. Are we going to learn more about his family background? It looks like things are going to get a lot more interesting for the Doctor.
 Yay!! It’s Martha!!
 Sycorax? Christmas Invasion?
 More so than normal, that is
 The numbers don’t necessarily make much sense, of course
 Nice back reference, that
 You remember, the Cloudbase-style flying aircraft carrier thingy