The fourth series of The Diary of River Song is being released today. In this new series River Song (Alex Kingston) meets the fourth incarnation of her husband (Tom Baker), and a threat like none she's ever encountered before†¦

With troublesome fellow academics, her own companions, a foe that can re-write time until they’re victorious, and of course the infamous, infectious Fourth Doctor, has River bitten off more than she can chew?

The Diary of River Song – Series Four is out now.

When River Song visits a place where time has vanished, a genie escapes its bottle…

The Discordia are freed – nihilistic time pirates, in devilish form, altering the past to make sure they never lose.

This time, River may have met her match. And involving the Doctor can only make things worse…

Script editor Matt Fitton explains more about this next set of adventures for the Doctor’s wife: “For this series, we wanted to give River an adversary to match her, a real threat, so producer David Richardson and I set about thinking. For a time, we talked about possibly using the Daleks, but in the end decided on something original, so we created the Discordia – one of whom is the handsome devil you can see on the cover.

“With no Time Lords to police things, the Discordia are essentially time pirates who can go back and re-engineer themselves and their evolution, to make themselves as intimidating as possible – and make sure they always win.

“They look like devils in the Hieronymus Bosch tradition, and they have rotating gun arms which spin around to whatever weapon the occasion demands.” More details can be found in July’s Vortex magazine.

The Diary of River Song – Series Four is available now at £23 on CD or £20 on download.

The Diary of River Song – Series Four can also be purchased as a bundle with The Diary of River Song – Series Five, to be released in January 2019, at the price of £45 on CD and £40 on download (all CD purchases from the Big Finish website unlock a download exclusive from the Big Finish website and app).

More details on The Diary of River Song – Series Five, where River faces off against four incarnations of the Master, can be found here.