The Claws of Axos

The Claws of Axos is the third serial of the eighth season of the British science fiction television series Doctor Who, which was first broadcast in four weekly parts on BBC1 from 13 March to 3 April 1971.

In the serial, set in Britain, the alien organism Axos spreads its Axonite particles across the Earth to allow itself to feed on all life on the planet.

A group of aliens calling themselves the Axons land on Earth, desperately in need of fuel. They propose to exchange the miracle substance they call Axonite for some much-needed energy. Axonite is introduced as a "thinking" molecule that can replicate any substance. However, it turns out that the ship, and the Axons themselves, are all a single organism called Axos, whose purpose is to feed itself by draining all energy through the Axonite (which is just a part of itself), including the energy of every life form on Earth. The deception about the Axonite's beneficial properties was to facilitate the distribution of Axonite across the globe, and help end world hunger, given the property of Axonite being able to enlarge and multiply any given matter.

Meanwhile, the Master, who was captured by Axos and used his knowledge of Earth as a bargaining chip for his life and freedom, escapes Axos and makes his way to the Third Doctor's TARDIS—his own having been seized by Axos. He plans to repair it to escape from Earth.

Axos itself becomes interested in the Doctor's knowledge of time travel and takes him prisoner aboard itself. It now plans to broaden its feeding base by travelling through time as well as space. The Doctor, realising this, plans to trick Axos into linking up its drive unit to his TARDIS so that he can send Axos into a perpetual time loop. After fooling the Master into completing the repairs on his TARDIS, the Doctor does just that. This results in every part of Axos dematerialising from Earth, including the Axon automatons and the Axonite.

At the end, with the Master having escaped in his own TARDIS during the confusion aboard Axos, the Doctor returns to Earth, but not of his own volition. The Time Lords have programmed the TARDIS to always return to Earth, making the Doctor, as he notes, "some kind of a galactic yo-yo!".

In late 1969, script editor Terrance Dicks contacted new writing duo Bob Baker and Dave Martin after reading a draft script they had sent around the BBC for another production, A Man's Life. After offering the duo a seven-part story in November 1969 for Doctor Who's eighth season, Baker and Martin submitted some various storylines they had. Despite the storylines not being suitable for a serial, Dicks commissioned an opening episode from them on 1 December, but as part of a six-parter, rather than a seven-parter.

The original storyline for the serial was set in central London, with Battersea Power Station taking the place of Nuton Power Complex. However, the serial would have been too expensive to make on the budget available, and Dicks promptly told the writing pair to scale down the story. After going back to the storyline stage, they decided to set the story just outside London, and excluded the large action scenes set in space and around major landmarks in London.