On the planet Marinus, the Doctor and his companions are enlisted by Arbitan to seek out the keys to an ancient and powerful machine. Their quest takes them across time and space; will they be able to return the keys before Marinus falls under the control of the alien Voord? (Originally broadcast in six parts.) Written by
Did You Know?
A scene cut from the script at the start of the episode revealed that the reason the Doctor and Susan had been on Earth in 1963 at the start of the series was because the Doctor had visited the British Broadcasting Corporation to get help repairing the colour scanner in the TARDIS, which was showing only monochrome images. He had been in such a bad mood upon his return to the TARDIS because the BBC had been "infernally secretive". See more
The model used in place of the Voord falling to its doom turns sideways as it falls, revealing that it is a two-dimensional cut-out. See more
For the sake of all my people, I hope you succeed.