Classic Who S18 • Serial 7 · (4 episodes)
Logopolis
The Doctor goes to Logopolis to repair the TARDIS' chameleon circuit, not knowing that a shadowy watcher is spying on him.
Meanwhile, his old enemy the Master has only recently gained secure longevity by possessing the body of Tremas, and revels in his safety. He has plans of his own for the planet of mathematicians, Logopolis, and a plan that could spell doom for the entire universe.
4 Episodes:
Deciding to repair the TARDIS' chameleon circuit, the Doctor goes to Earth to find a real police box. But an old enemy is one step ahead of him.
The Doctor, aware that his time may soon be ending, travels to the Logopolis where a series of fateful events are set in motion.
With Nyssa from Traken unexpectedly rejoining the group, Adric aids the Monitor of Logopolis in trying to save the Doctor before time runs out. The Master, at liberty to prepare, is finally ready to reveal his true target, which unknowingly sets off the biggest catastrophe of all time.
With the universe collapsing, the Doctor forms an uneasy alliance with the Master to save it. In case all does not go well, the Watcher takes the Doctor's companions to a safe place, but his plans for them don't stop there. The one hope for all lies back on Earth.