The first of 2025’s Third Doctor Adventures box sets brings together the UNIT team of Doctor Who Season 7 in a brand-new adventure which – like the TV stories of that era – is told over seven episodes. 

In Doctor Who and the Brain Drain, the Doctor (Tim Treloar) is getting used to his recent exile on Earth and settling into his role as UNIT’s scientific advisor when he’s dispatched to Scotland on his latest mission. 

Accompanying him are Dr Liz Shaw (Daisy Ashford) and Brigadier Lethbridge-Stewart (Jon Culshaw). This fledgling team will have to pool all their skills, as monsters, ghosts and more threats await them. 

Doctor Who – The Third Doctor Adventures: Doctor Who and the Brain Drain is now available to pre-order as a collector’s edition CD box set (+ download for just £24.99) or a digital download only (for just £19.99), exclusively here.

A newly exiled Doctor accompanies Liz Shaw and the Brigadier to a symposium held in an imposing Scottish castle. Professor MacLeod and her son have developed a new treatment for memory loss and a possible cure for dementia. 

As the Doctor investigates sightings of strange mythical creatures, and ghosts are unleashed in the castle’s corridors, Liz and the Brigadier search for a connection. 

Just what is happening to the energy produced by the MacLeods’ revolutionary treatment? And what is the strange creature that hides in the castle grounds? 

The supporting cast of Doctor Who and the Brain Drain includes Rosalyn Landor (known for classic films including The Devil Rides Out and The Amazing Mr Blunden), as well as Mark Elstob, Susan Harrison, Glen McCready, and Callum Pardoe. 

The script is co-written by Nicholas Briggs, Big Finish’s executive producer, and Richard James, an experienced writer of stage plays and thriller novels, here making his Big Finish debut. 

Nicholas Briggs said: “My wife had been editing one of Richard’s books and said to me, he writes beautifully. He also knows his old Doctor Who and has a very clear sense of the Third Doctor era, so I asked him for ideas for Third Doctor stories. He sent this one pitch and it had something about it that I really liked. It felt like Doctor Who, but also like an old-fashioned Sunday afternoon teatime adventure.” 

Richard James added: “Nick’s written not just some of the best Doctor Who for Big Finish, but some of the best scripts I've ever heard. I love his Eighth Doctor and Lucie Miller stories; I remember listening to those avidly. So I was delighted to co-write with him.  

“And I never knew I was such a big fan of the Third Doctor era until I started writing the script and suddenly I could hear the Doctor, the Brigadier and Liz Shaw in my head. It was quite extraordinary. Liz is really interesting, and was criminally underused at the time, so I gave her the opportunity to come to the fore and do her own investigating. 

“It was amazing hearing those words coming back to me by the people who were born to say them. Not just the likes of Tim Treloar, Daisy Ashford and Jon Culshaw as the triumvirate that we all know and love, but also the incredible supporting cast.” 

Big Finish listeners can save money by purchasing Doctor Who and the Brain Drain in a bundle with 2025’s second Third Doctor Adventures box set (Title TBC), which is due for release in October, for just £47 (collector’s edition CD box set + download) or £38 (download only). 
  
Alternatively, listeners can buy this series as part of a bundle of all 15 Classic Doctor Who box sets released in 2025 for £335 (collector’s edition CD box set + download) or £275 (download only).   

All the above prices include the special pre-order discount and are subject to change after general release. 

Please note that Big Finish is currently operating a digital-first release schedule. The mail-out of collector’s edition CDs may be delayed due to factors beyond our control, 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.