Doctor Who and the Planet of the Spiders

Arak said patiently, ‘Our ancestors brought them from
Earth.’
‘Colonists?’,
Arak nodded. ‘Four hundred and thirty-three years ago, a
starship came out of its time jump with no power left and
crashed on Metebelis Three.’ He spoke in a sort of formal chant.
The Doctor looked at him curiously. ‘You seem to know the
story very well.’
‘My father taught it to me – and his to him.’
‘A detailed oral tradition. Fascinating! And what about the
spiders?’
Arak was surprised. ‘I thought you knew – they came from
Earth too. We think there must have been a colony of them
somewhere on the ship. When it crashed, they were blown free.
The wind carried them to the blue mountain.’
‘Yes of course,’ said the Doctor. It was all falling into place
now.
‘The Earth Spiders went to live in the blue mountains,’ said
Arak. ‘The crystals enlarged the spiders’ bodies and minds.’
Tuar took up the story. ‘Over the years the eight-legs grew
larger and larger, cleverer and cleverer. Their minds acquired
the power to control humans – to blast us down with pure
thought. Eventually they took over.’
‘How did they manage to do that – and how do they stay in
charge?’
‘With the help of traitors,’ said Arak bitterly. ‘When they saw
how things were going, some humans joined the eight-legs. Now
they help to enslave the rest of us. They don’t work in the fields.
They get the pick of the crops, while we nearly starve. The
Spiders even share a few of their powers with them – just to keep
the rest of us in line.’
‘Like those jewelled staves,’ said the Doctor. ‘They must act
as telepathic amplifiers.’ Though the technique could work