The second half of a two-parter has one job: pay off the mess the first half made. The Sontaran Stratagem left us with four hundred million cars pumping poison into the sky, an old man sealed in a gassing car in his own driveway, and a fleet of very short soldiers in orbit having the time of their lives. “The Poison Sky” does that competently rather than brilliantly — it’s the most conventional hour of the season so far, all corridors and countdowns and soldiers shouting into radios. But it gives Donna a genuinely good solo run, it finds an unexpectedly moving ending for its most irritating character, and it lets the Doctor be quietly, seriously angry about something worth being angry about.
Axes and Atmospheres
We left Wilf choking in a locked car, and the resolution is perfect: Sylvia Noble puts an axe through the windscreen. It’s a brilliant little beat — the mother who has spent two episodes being witheringly unimpressed by everything turns out to be the one who runs at a problem with a hatchet. The Nobles continue to be the best supporting family the show has had since the Tylers.
The scale of the threat is well handled. This isn’t an invasion fleet in the sky; it’s every car on Earth belching poison at once, cities vanishing under yellow fog, hospitals filling up. The Sontarans aren’t conquering the planet in the usual sense — they’re converting it, turning the whole atmosphere into a soup suitable for growing clones, because a war with the Rutans needs bodies and Earth is a conveniently placed nursery. Humanity isn’t even the enemy here. It’s just in the way of the breeding programme, which is a properly dismissive kind of villainy.
The imagery earns it, too. There’s a genuinely unsettling stretch in the middle where the streets simply empty — abandoned traffic sitting in the road, yellow fog rolling between semi-detached houses, an entire country told to stay indoors and breathe through wet towels. It’s a very British sort of apocalypse, all civil-defence broadcasts and people taping up their window frames, and it’s considerably more effective than the space battle that follows it. The show has always been good at catastrophe rendered in suburban terms, and this is a strong example.
UNIT’s Bad Day
The military response is the most interesting failure in the episode. UNIT throws everything it has at the Sontaran ship and it simply doesn’t work: the Sontarans deploy a signal that expands the copper in bullet casings so rifles jam in soldiers’ hands. An entire army is disarmed by metallurgy. Colonel Mace’s counter-move — bringing in the Valiant, the vast flying carrier we last saw serving as the Master’s throne room in The Sound of Drums — is a nice piece of continuity, and the sight of that thing rising through the fog to open fire is the best image in the episode.
The Doctor’s relationship with all this stays prickly, which I appreciated. He works alongside them, he uses what they can do, and he never once pretends to like it. The argument the two-parter started about whether his contempt for soldiers is entirely fair doesn’t get resolved here either, and the show is right not to force it.
Donna Alone
The best material belongs to Donna, and it’s the first time this season has properly tested her. The Doctor sends her back to the TARDIS and then, over the phone, talks her through sabotaging the Sontaran ship’s conversion machinery — alone, unarmed, in a corridor full of soldiers who would kill her on sight, with nothing but a mallet and a set of instructions. She is visibly terrified throughout, and she does it anyway. Catherine Tate plays the fear straight rather than for laughs, which is the correct choice, and the moment she flattens a Sontaran with a swing of the mallet is enormously satisfying.
It matters because Donna has spent her run being the person who tells the Doctor what to do rather than the person who does the running. Since the two of them put their hands on that lever together in The Fires of Pompeii, the show has been building her as an equal rather than a passenger, and this is where it cashes that in. She’s not clever like Martha or fearless like Rose. She’s an ordinary woman doing something appalling because it needs doing, and that’s arguably better.
Martha, freed from her tank, gets to be useful too — using the clone’s link to the Sontaran systems, and getting a genuinely odd little scene with her own duplicate as it dies. The clone thread doesn’t amount to much in the end, but it gives Freema Agyeman something to play beyond exposition.
The Boy Who Wanted to Matter
The resolution is where the episode surprises. The Doctor builds a device to ignite the gas and burn the atmosphere clean, then teleports to the Sontaran ship — not to use it, but to offer them a way out first. Leave, or he sets fire to the sky and everyone in this room dies with it. Staal, being a Sontaran, chooses the glorious death without hesitating.
That offer is worth pausing on. He didn’t have to make it. He had the device built, the ship in range and every justification he could possibly want, and he stood there and gave them a way out anyway — to a species that had just spent a day trying to suffocate a planet for breeding space. It’s the clearest statement yet of the line this Doctor keeps trying to hold: one chance, offered honestly, even to people who are obviously going to throw it back at him.
And then Luke Rattigan takes the Doctor’s place. The spoilt, insufferable teenager who sold his planet for a bit of flattery has spent the episode watching the Sontarans make it very clear they were always going to exterminate him and his students. So he shoves the Doctor back through the teleport, triggers the device himself, and goes up with the ship. It’s a genuinely affecting turn, mostly because the episode never asks us to like him — he doesn’t get a redemption speech, just a boy who finally understood what he’d done and made one correct decision at the last possible moment.
Meanwhile the Doctor was entirely prepared to die doing it, which nobody remarks on, and which is becoming a pattern worth watching.
What The Poison Sky Leaves Us With
Sturdy, unspectacular, with a better heart than its plot deserves. Here’s what it plants:
- Donna, tested. Alone on an enemy ship with a mallet and no clever plan. Frightened the whole way through and effective anyway — her best hour so far.
- Sylvia with an axe. The single funniest and most satisfying beat in the episode, and a useful reminder that Donna comes from somewhere.
- An army that can’t help. Disarming UNIT with a copper-expansion signal is a smart way to make the military irrelevant without making them stupid.
- Rattigan’s exit. No speech, no forgiveness, just one good decision from a thoroughly unpleasant boy. More effective than a redemption arc would have been.
- A Doctor happy to die. He walked onto that ship intending not to come back, and the episode passes over it without comment. That’s twice this season now.
Rating: 3/5 — The most routine story of the run, heavy on corridors and countdown clocks, and the Sontarans lose a little menace once they’re just shouting at soldiers. But Donna’s solo mission and Rattigan’s ending lift it, and it never drags.
The sky burns clean, a boy nobody liked saves the world by finally doing the one decent thing still available to him, and Sylvia Noble goes at a car windscreen with an axe. Not a classic by any measure — but the bits that work, work rather well, and Donna Noble walked onto an enemy warship armed with a mallet. I’ll take it.
