Doctor Who reveals new details about Sacha Dhawan's Master in spin-off stories

The set will see the Master revel in "creating chaos" across the universe as he gets to know his latest form, with the synopsis promising "cunning new schemes" from the classic baddie – and no Doctor to stand in his way!

Self-Help finds the Master with a typically "diabolical scheme on the go", but also a deep sense of unease characterised as an existential crisis. Can he get out of this funk?

Valentine said: "Where Sacha's Master fits into the timeline is a deliberate mystery.

"I thought it would be fun, in the context of starting a fresh series with him as our antihero, to embrace his identity crisis in a big way and make that the point of the story – he doesn't know where he fits in, and that's a huge source of anxiety for him."

The Clockwork Swan takes place at a cultural theme park named Historica Dramatica, where a whodunnit play is ready to be performed – that is, until the cast themselves start being murdered one-by-one.

A mysterious stranger who calls himself LeMaitre steps in to crack the case – although you probably know them by a different name.

Cook said: "The Master has such a wonderful history of putting on personas and adopting monikers and different costumes.

"People tend not to notice that he’s not always doing them particularly well! It's so great to add to that mythos, with him hamming it up trying to portray a Poirot or Sherlock Holmes-style detective."

Last but not least, The Good Life sees the Master wash up on an island of holy men and women, who are shocked to see a rare new person arrive – and are suspicious of whether he is a "saint or a sinner". And then, things start going wrong...

McCormack said: "My initial pitch was that we do something similar to Mervyn Peake's novel Mr Pye.

"The hero of that novel arrives on the island of Sark, where he carries out so many good deeds that he begins to sprout angel wings. I really liked the idea of the Master trying to be good but not being very good at it."

Inner Demons will be followed by a second box set of stories starring Sacha Dhawan's Master, due for release in September 2025.

Fans have the option to pre-order both sets together, or just Inner Demons, from the Big Finish website.

Doctor Who is available to stream on BBC iPlayer.

Check out more of our Sci-Fi coverage or visit our TV Guide and Streaming Guide to find out what's on. For more from the biggest stars in TV, listen to The Radio Times Podcast.