All of the Doctor's incarnations are in crisis when The Rani creates a time-loop in the East-end of London in this 30th Anniversary Special.

Arriving on the barren world of Androzani Minor, the Doctor and Peri find themselves embroiled in a long running, literal underground war. At the heart of the conflict is a substance called Spectrox - both valuable and deadly! The Doctor & Peri wind up being poisoned by the material, which is killing them slowly and painfully unless they can find a cure. As the conflict heats up and the situation gets more desperate, the Doctor realises time is running out - both for Peri and himself...

The Doctor's past incarnations are taken out of time by a forbidden time scoop device. The fourth Doctor becomes trapped in the vortex but the others find themselves, together with a number of their old companions, with the fifth Doctor and his companions in the Death Zone on their home planet Gallifrey.
Here they face a Dalek, a Yeti, a quicksilver Raston Warrior Robot and numerous Cybermen. Also present is the Master, who has been summoned by the High Council of Time Lords to help the Doctor. It turns out that President Borusa is the mysterious operator of the time scoop. He aims to use the Doctors to breach the defences of the Dark Tower - Rassilon's tomb - so that he can enter there and claim immortality.
When he does so, however, he is condemned by Rassilon to eternal existence in the form of a living statue.