Professor Litefoot and Henry Gordon Jago are accustomed to the murky fog of Victorian London and the palatable pints of half and half at the Red Tavern. They are not used to travelling through time and space with their old friend the Doctor. And now they find themselves whisked off to the planet Venus in the distant future, at a time when warrior women rule from a floating city in the clouds. There’s a mystery here, one that the Grand Empress Vulpina intends to keep secret. Even if it means destroying these visitors from the long-dead planet Earth....

The web of time is stretched to breaking. History is leaking like a sieve. In the Citadel of Gallifrey, the Time Lords fear the end of everything that is, everything that was...everything that will be. The Doctor holds the Time Lords' only hope - but exactly what lengths will the Celestial Intervention Agency go to in their efforts to retrieve something important from within his TARDIS? What has caused Imperiatrix Romanadvoratrelundar to declare war on the rest of creation? And can an old nursery rhyme about a monster called Zagreus really be coming true?

October 1944: as World War II draws towards its conclusion, a Nazi defeat begins to seem almost inevitable. But that might be about to change.... Two intruders are captured in the grounds of Colditz Castle, the most secure POW camp in Germany. At first the guards think they're dealing with British spies. But the strangers arrived in an advanced travelling machine, the likes of which they've never seen before. With this Tardis in their hands, the Third Reich might triumph after all.

The universe stands on the brink of a dimensional crisis - and the Doctor and Raine are pulled into the very epicentre of it. Meanwhile, on Earth, UNIT scientific advisor Dr Elizabeth Klein and an incarnation of the Doctor she's never encountered before are tested to the limit by a series of bizarre, alien invasions. At the heart of it all is a terrible secret, almost as old as the Time Lords themselves.

On a dark, frozen planet where no planet should be, in a doomed city with a sky of stone, the last denizens of Earth's long-lost twin will pay any price to survive, even if the laser scalpels cost them their love and hate and humanity. And in the mat-infested streets, around teatime, the Doctor and Nyssa unearth a black market in secondhand body parts and run the gauntlet of augmented police and their augmented horses.