The First Doctor Unbound, a brand-new trilogy of fast-paced, movie-style audio dramas starring David Bradley as the Doctor, continues next year with Return to Marinus. 

In this sequel to the 1964 TV serial The Keys of Marinus, 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! 

Doctor Who – The First Doctor Unbound: Return to Marinus is now available to purchase for just £13.99 (download to own) or £16.99 (download to own + collector's edition 2-disc CD), exclusively here. Please note: the collector’s edition CD is strictly limited to 1,000 copies and will not be re-pressed. 

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 Big Finish creative director Nicholas Briggs as the Daleks, as well as Joseph Millson (The Sarah Jane Adventures) and Timothy Blore (Rivals), among other names yet to be announced. 

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.” 

Big Finish listeners can save money by pre-ordering Return to Marinus in a multi-buy bundle with the third The First Doctor Unbound volume, which is due to be released in May 2027, for just £26 (download to own) or £32 (download to own + collector’s edition CD). 

All the above prices (including pre-order and multibuy bundle discounts) are fixed for a limited time only and guaranteed no later than 30 November 2025. 

Big Finish is currently operating a digital-first release schedule. The mailout of collector’s edition CDs will be delayed, but all purchases of this release unlock a digital copy that can be immediately downloaded or played on the Big Finish app from the release date.