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.
The Master is loose on Logopolis and is determined to learn its secret. But there is more at stake than he realises and his meddling has endangered the entire universe.
With the fate of the universe hanging in the balance, the Doctor and the Master are forced to return to Earth and carry out their plan. But for the Fourth Doctor, it's the end…