The day after tomorrow - and the Vrezian Confederacy and the J'arrodic Federation have brought their 'honorable' air-war to Earth. They're not here to invade, and they're being exceptionally considerate about collateral damage, all things considered. But human air travel is at a standstill, our culture is collapsing, the skies are clogged with toxic smog. And UNIT can't do a thing, as the aliens vaporize the weapons stockpile of any country that dares interfere! The deadlock needs a peaceful and clever solution; let's hope the Doctor is up to the job! And in the middle of it all, Alice is given a shocking offer she dare not refuse!