In July, Counter-Measures face their darkest hour - and you can discover their origins with this month's listeners title...

Each month, Big Finish makes one download from its extensive back catalogue available at a bargain price.

This month our chosen title is Doctor Who: 1963: The Assassination Games. This main range story from writer John Dorney reunites the Seventh Doctor (Sylvester McCoy) and Ace (Sophie Aldred) with Group Captain Gilmore (Simon Williams), Rachel Jensen (Pamela Salem) and Allison Williams (Karen Gledhill): last seen in 1988's Rememberance of the Daleks.

London. The end of November, 1963. A time of change. The old guard are being swept away by the white heat of technology. Political scandals are the talk of the town. Britain tries to maintain its international role; fanatics assassinate charismatic politicians and Group Captain Ian Gilmore is trying to get his fledgling Counter-Measures unit off the ground.

When his life is saved by a familiar umbrella-bearing figure, he knows something terrible is going on. Whilst Rachel investigates an enigmatic millionaire and Allison goes undercover in an extremist organisation, Gilmore discovers a sinister plot with roots a century old.

The Doctor and Ace are back in town. A new dawn is coming. It's time for everyone… to see the Light.

This thrilling story sets up events for Big Finish's critically acclaimed spin-off series Counter-Measures, continuing the adventures of Gilmore, Rachel and Allison, alongside the manipulative Sir Toby Kinsella (Hugh Ross).

You can download Doctor Who: 1963: The Assassination Game today for just £2.99. Join us to discuss the title in our dedicated listeners forum thread. All opinions and observations are welcome!

The Intrusion Counter-Measures Group faces their darkest hour this month with the release of Counter-Measures: Series 4. You can catch up on the first three volumes here.