Originally transmitted in 1961, The Avengers was a ground-breaking crime adventure series, following the activities of John Steed, a suave secret agent investigating Britain's strangest crimes - aided by the dashing Dr David Keel. Together, they pitted themselves against the underworld's most devious and colourful villains.

Sadly, 24 of the 26 episodes of the first series no longer exist; but Big Finish have revisited these missing episodes in a series of audio box sets, starring Anthony Howell as Dr Keel, Julian Wadham as Steed, and Lucy Briggs-Owen as Carol Wilson.

This May Day weekend, you can enjoy the first three box-sets at the special offer price of £20 each on CD or £15 to download. Each story has been adapted by John Dorney from the original television scripts to recreate the thrilling origins of one of Britain's most iconic series.

The Avengers: The Lost Episodes Volume 1 explores the first meeting of Steed and Keel, following the murder of the Doctor's beloved fiancée Peggy (Camilla Power). The resulting investigation places the Avengers on the trail of warring drug gangs in the heart of London's underworld.

Before long, Steed is recruiting Keel for other secret missions, including a face-off with forgers and a chase to prevent an international conspiracy involving laundry and taxidermy! The first series also features Colin Baker, Tim Bentinck, Terry Molloy, Nicholas Briggs, Beth Chalmers and Sophie Aldred.

Carol Wilson is brought further into the fold in The Avengers: The Lost Episodes Volume 2, which features horror in a hairdressing salon, animal-loving blackmailers, deadly dancers and a radioactive man! Guest stars in the second box-set include Richard Franklin, Jacqueline King, Dan Starkey, Anjella Mackintosh and Richard Hope. 

The Avengers: The Lost Episodes Volume 3 continues the trend, with tales of prison breaks, stolen diamonds, assassins in Africa and a toy shop of terrors, featuring Miranda Raison, Phillip Pope and Sarah Lark.

Each of these box-sets is priced at just £20 on CD or £15 to download until noon on Tuesday May 3rd – so order now! As with the majority of Big Finish releases, a digital copy is included with all CD orders; so you won't need to wait to enjoy the stories!

Steed and Keel's investigations continue in The Avengers: The Lost Episodes Volume 4 and Volume 5, with Volume 6 and Volume 7 available to pre-order.

The colourful missions of Steed and Mrs Emma Peel (Olivia Poulet) are brought to life in the recently-released The Avengers – Steed and Mrs Peel: The Comic Strip Adaptations Volume 1, which is still available to order at its pre-order price of £25 on CD or £20 to download. You can also enjoy these new stories as part of a special money-saving bundle alongside Volume 2 and a graphic novel reprinting the original Diana magazine comic strips.

For an exclusive preview of this new series, you can download an extended excerpt for free here or listen via the SoundCloud player below: