As a mathematician Dr Hannah Fry specialises in understanding patterns of human behaviour.
And nowhere does the human factor smash headlong into the reality of numbers than in the secretive world of code-breaking.
So she's delved into the BBC Radio Archive to present a fascinating selection of programmes all about codes, secrets and ciphers. And if you have a pen and paper handy she'll be presenting you with a code which you can try to crack, offering hints which will help throughout the programme.
On hand to help are two experts who between them have got numbers and words covered. Bobby Seagull is a maths teacher and author of The Life-changing Magic of Numbers and Richard Rogan is the editor of The Times Cryptic Crossword.
They'll share their insights into codes, and give their takes on a fascinating selection from the archive. Featuring:
A creepy delve into the world of cold war number stations - Simon Fanshawe investigates in Tracking the Lincolnshire Poacher.
David Baddiel tries to understand Cryptic Crosswords.
A famous example of a literary code in Sir Arthur Conan Doyle's Sherlock Holmes story The Adventure of the Dancing Men, adapted by Bert Coules.
In The Bletchley Girls, Tessa Dunlop tracks the stories of just a few of the often sidelined women who populated the codebreaking station Bletchley Park in the Second World War, and played their part in significantly shortening the length of the conflict.
And in a special episode of The Infinite Monkey Cage Katy Brand joins the team in the security agency GCHQ to talk ciphers.
So get your pen ready, join Dr Hannah Fry, listen out for the clues - and get cracking.
Producer: Kevin Core
Made for BBC Radio 4 Extra and first broadcast in February 2020.
Dr Hannah Fry brings you the best in codes, ciphers and secrets from the BBC Radio archive