The Doctor takes the TARDIS into the future where many great scientific leaps are taking place. But every new advance has its risks – and some of these risks are deadlier than others. 

The Fourth Doctor (Tom Baker) and Sarah Jane Smith (Sadie Miller) will take three trips forward in time in Lethal Progress, a box set of brand-new audio adventures set during Season 13 of Doctor Who. 

But the course of the future rarely runs smooth, and everywhere the TARDIS lands, danger awaits. 

A British space expedition encounters a mysterious village, a pioneering hyperspace journey leads to a race to avert disaster, and Sarah finds herself in one of her most terrifying experiences yet – having to perform onstage! 

Doctor Who – The Fourth Doctor Adventures: Lethal Progress is now available to pre-order for just £19.99 (download to own) or £24.99 (download to own + collector’s edition 3-disc CD box set) exclusively here. Please note: the collector’s edition CD box set is strictly limited to 1,500 copies and will not be re-pressed. 

The Doctor’s three new trips in time are: 

Green and Pleasant Planet by Tim Foley 

The Doctor and Sarah find themselves exploring an alien world alongside a British space expedition. It’s never been visited before... so what’s a model village doing on the surface of the planet? 

Finding the answer may prove deadly. 

The Continuum by John Dorney 

The Doctor and Sarah land on the space-station Daedalus on the day it makes history. 

The first journey through hyperspace has just been completed. But it hasn’t gone as smoothly as posterity suggests. 

Something terrible is happening – and the clock is ticking down. 

The Audience by Lizzie Hopley 

A cultural festival on Gakoria should be light relief for the TARDIS crew. 

But when one of the cast of a play dies, Sarah has to join the troupe. And the Audience on this world are very demanding. 

Because on this planet... the play’s the thing. 

The guest cast of Lethal Progress includes Jake Wardle (Twin Peaks), Alexander Cobb (Marvel’s Moon Knight), and Esther Coles (Enola Holmes), plus further names to be announced. 

Producer David Richardson said: “The Doctor and Sarah Jane head out among the stars… and they’re indomitable! After the cosily Earth-bound The Ministry of Death, the travellers visit other worlds and other times in Lethal Progress, which, as the title might suggest, finds that scientific advancement doesn’t always benefit the human race. Expect three imaginative and thrilling adventures from the minds of the brilliant Lizzie Hopley, Tim Foley and John Dorney!”  

Writer John Dorney explained his episode: “I came into this story wanting to write something with a bit of horror but in a science fiction way. I was looking at different fictions for inspiration, like The Great God Pan and Event Horizon. Then I began to think about doing the whole thing as one long continuous scene; we’ve had a few ‘single take’ films like that in recent years, and I was curious to see what that would bring to a Doctor Who story.” 

And, the third episode’s writer Lizzie Hopley said: “Everyone says write what you know, so with this story, as I started off as an actress, I wanted to write something about that process in an alien environment. I’ve had some nightmare audiences, so this is basically a nightmare. I had to tone down the horror!” 

All three of 2026’s Fourth Doctor Adventures box sets (due for release in March, June and September) can be pre-ordered together in a multibuy bundle for just £57 (download to own) or £70.50 (download to own + collector’s edition CD). 

Alternatively, listeners can buy this release as part of a bundle of all 15 Classic Doctor Who box sets released in 2026 for just £285 (download to own) or £352.50 (download to own + collector’s edition CD box set). 

All the above prices (including pre-order and multibuy bundle discounts) are fixed for a limited time only and guaranteed no later than 30 April 2026. 

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.