Earth is choking, UNIT is panicking, and the Doctor’s biggest weapon is a remote control.
Short Synopsis
The Sontarans activate their ATMOS system, filling Earth’s skies with poisonous gas. The Doctor, Donna, and Martha fight to stop them, with UNIT throwing missiles around for good measure. Meanwhile, boy-genius Rattigan realizes that siding with potatoes was a bad idea.
Extended Storyline
We open exactly where we left off: the entire planet’s cars are belching out a toxic green fog. UNIT soldiers, bless them, are charging bravely into the situation armed with guns (which are about as useful against gas as a chocolate teapot). The Doctor frantically tries to disable an ATMOS unit, while General Staal and his Sontaran warriors gloat from orbit like smug potatoes at a bake-off.
Donna, ever the MVP, proves once again why she’s the best companion: while UNIT plays shooty-bang, she sneaks into the Sontaran ship. Armed with little more than sass and curiosity, she discovers the TARDIS trapped onboard. Cue tense “phone home” moment where she uses the Doctor’s spare phone to call Gramps Wilf — who is trapped in his car by ATMOS and nearly suffocated. Donna’s panic is raw, Wilf is heartbreaking, and suddenly this isn’t just an alien invasion; it’s a family in danger.
Meanwhile, Martha’s subplot goes full body-horror. The Sontarans have cloned her, creating an evil duplicate with all her memories but none of her morals. Real Martha is trapped in a gooey tank, Fake Martha is sabotaging UNIT, and the Doctor is left trying not to scream “Could this day GET any worse?”
Back on Earth, UNIT decides subtlety is overrated and fires missiles at the Sontaran ship. The results? About as effective as throwing pebbles at a tank. The Sontarans laugh it off and deploy their ground troops, who march around like militaristic potatoes with guns. (To be fair, they’re more threatening than Cybermen in slow-walk mode, but only just.)
The Doctor eventually figures out that the ATMOS system can be reprogrammed. With a bit of tinkering (read: technobabble), he turns the system into a planet-wide decontamination unit. But he needs someone to stay behind and push the big red button of sacrifice. The Doctor’s ready to do it himself — noble self-sacrifice is his Tuesday — but Rattigan, our insufferable boy genius, finally grows a spine. Realizing he’s been played by the Sontarans and his “chosen elite” science kids have ditched him, he sacrifices himself to activate the system, redeeming himself in the least annoying way possible.
The skies clear, the humans breathe again, and the Sontaran fleet looks smug right up until it explodes in a ball of fiery potato mash. Victory! Humanity survives to keep inventing dodgy tech, UNIT gets a win in the books, and the Doctor celebrates with his favorite coping mechanism: running away before the paperwork starts.
But there’s a kicker. At the end of the episode, Martha steps into the TARDIS for a friendly farewell tour — only for the doors to slam shut, the controls to spark, and the TARDIS to dematerialize on its own. Translation: cliffhanger alert!Something big just hijacked our heroes, and it definitely isn’t going to involve tea and biscuits.