Doctor Who fans first saw Group Captain Gilmore (Simon Williams), Professor Rachel Jensen (Pamela Salem), and Professor Allison Williams (Karen Gledhill) battling Daleks. And then life got really difficult for them...

Teamed up with Sir Toby Kinsella on the Intrusion Counter-Measures Group (ICMG), the four have battled aliens and villains in 1960s settings across a range of adventures much regarded by Big Finish listeners, right up to this month's brand new release The New Counter-Measures - Who Killed Toby Kinsella?:

This weekend we celebrate the return of the ICMG with a range of special offers. Their second adventure with the Seventh Doctor - Doctor Who - 1963: Assassination Games is £6 on CD and £5 on Download, while the first three boxed sets are each £20 on CD and £15 on Download.

A year ago listeners were shocked by the events of Counter-Measures Series 4 - adventures you can experience right now for £25 on CD and £20 on Download. And we're not forgetting that ICMG had a significant part to play in the limited edition, epic four-story adventure The Worlds of Doctor Who, which for this weekend is £25 on CD (in a luxury book packaging) and £20 on Download.

Several bundles have been set up to give you money-saving prices on collections of the Counter-Measures releases, including all four Counter-Measures boxed sets (£85 on CD, £62 on Download), or all four sets along with Doctor Who - 1963: Assassination Games (£91 on CD, £65 on Download). There are also bundles collecting The New Counter-Measures: Who Killed Toby Kinsella? and December's The New Counter-Measures - Series 1 together for £42 on CD and £35 on Download.

Remember: as with most Big Finish releases, a purchase on CD instantly unlocks a download version in your account, so you can be listening moments after buying! A Big Finish app in the iOS store (with an Android version coming soon) enables you to listen on the go!

This offer ends at mid-day on Monday 25th July (UK time).