The spirit of Season 17 continues in a brand new adventure for the Fourth Doctor (Tom Baker), Romana (Lalla Ward) and K9 (John Leeson); who find themselves on board a time-travelling war machine...

Whilst travelling in the vortex, the TARDIS is struck by an advanced war machine - a Time Tank! Losing Romana, the Doctor and K9 pursue the Tank to Aoris, a world quite literally at war with itself.

Soldiers from the future are attacking the past of their own planet - gathering resources and stealing endangered species. But the past is not without weapons of its own - leaving deadly devices ready to trigger many years ahead after their enemies have been born.

Trapped at opposite ends of a temporal war, the Time Lords have two time zones to save. But who is in the right, and who in the wrong? And when history itself is against you, can anybody actually win?

Written by Jonathan Morris and starring Tom Baker, Lalla Ward, John Leeson, Simon Rouse, Tom Chadbon, Paul Panting, Emma Campbell-Jones, Laura Rees, Bryan Pilkington, Jane Slavin and John Banks, Doctor Who – The Fourth Doctor Adventures: The Paradox Planet is available to buy and download today from the Big Finish website. And remember, when you choose to buy this release on CD directly from Big Finish, you will also unlock instant access to a digital copy for download.

The adventure continues in April with Doctor Who: Legacy of Death. Can the Doctor save the same planet twice in the same day?

You can subscribe to the entire series today to enjoy additional savings. Four previous series of Fourth Doctor Adventures are still available to order now, with special bundles also available. Check out the entire range on our Fourth Doctor Collected page.