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The First Doctor Returns to Marinus for Big Finish’s Doctor Who Unbound

The First Doctor, played for Big Finish by David Bradley, will go back to the titular planet of The Keys of Marinus in the audio story, The First Doctor Unbound: Return to Marinus.

The First Doctor Unbound, a brand-new trilogy of fast-paced, movie-style audio dramas starring David Bradley (Twice Upon a Time) as the Doctor, continues next year this sequel to the 1964 TV serial, The Keys of Marinus, in which the Doctor and his companions, Susan (Claudia Grant), Ian (Jamie Glover), and Barbara (Jemma Powell), land once again on the planet of acid seas and glass beaches. But a century after their last visit, Marinus has changed, and new dangers await the time travellers… including their most deadly enemies, the Daleks!

Here’s what to expect from Return to Marinus:

The TARDIS has brought the Doctor and his companions back to the planet Marinus, one century after their previous visit. They are greeted as returning heroes, figures of legend. But something is amiss in the city of Millenius. Everybody lives in peace and harmony… whether they like it or not.

The explanation is obvious. Somebody has reactivated the Conscience Machine and is set on removing free will from Marinus. Somebody – or some old enemies of the Doctor…


The guest cast includes Nicholas Briggs as the Daleks, as well as Joseph Millson (Maria’s dad in The Sarah Jane Adventures) and Timothy Blore (Rivals).

Producer and director David O’Mahony said:

“With the First Doctor Unbound series, we took inspiration from the Peter Cushing films, with bold storylines, high-stakes drama, and the kind of twists and turns that would have been thrilling in a cinema. Return to Marinus kicks the trilogy into high gear – with the Voord and my personal favourite villains involved, this is a high-octane, fast-paced adventure.

“Our ensemble of actors turn their incredible talents to exploring a whole new corner of the universe. I really hope everyone enjoys this middle part of the story and will be chomping at the bit for our third instalment, coming in 2027.”

Writer Jonathan Morris added:

“I’ve always loved The Keys of Marinus, ever since I read the novelisation. The only Doctor Who planet with multiple societies and biomes – a whole world. But we only saw five aspects of it on television – how much more might there be to explore? What about its deserts, or volcanoes, or the undersea kingdom of the Voord?

“So the chance to write a sequel story – in glorious, technicolour widescreen – was a dream come true, because this is the sort of thing I dream about. Not only to find out what happened to its peoples one hundred years after that first adventure, but also to revisit its themes and widen the canvas even further. And, if that wasn’t enough, it has the Daleks in it too.”

The First Doctor Unbound: Return to Marinus is now available to pre-order for £13.99 (download to own) or £16.99 (download to own and two-disc CD), and is released in January 2026. The CD is strictly limited to 1,000 copies and will not be repressed.

Philip Bates

Editor and co-founder of the Doctor Who Companion. When he’s not watching television, reading books ‘n’ Marvel comics, listening to The Killers, and obsessing over script ideas, Philip Bates pretends to be a freelance writer. He enjoys collecting everything. Writer of The Black Archive: The Pandorica Opens/ The Big Bang, 100 Objects of Doctor Who, and Companions: More Than Sixty Years of Doctor Who Assistants.

The First Doctor Returns to Marinus for Big Finish’s Doctor Who Unbound

by Philip Bates time to read: 2 min
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