TV tonight: Rob Rinder is inside the UK’s most notorious prison

Britain Behind Bars: A Secret History

9pm, Channel 4

TV judge Rob Rinder is investigating a world of riots, brutal regimes and infamous hangmen in this eye-opening three-parter telling the tale of Britain’s prisons. He also speaks to former inmates who say today’s system is actually much like it was in the past. His first stop is HMP Dartmoor in Devon, which has the reputation of being one of the nation’s most notorious jails. Hollie Richardson

McDonald & Dodds

8pm, ITV1

The enjoyably offbeat cosy-crime drama about a chalk-and-cheese detective duo returns with a new three-part case to get stuck into. When a middle-aged woman is found shot dead, DNA tests reveal her identity: Anne Holgate, who went missing on her way home from school 38 years ago. HR

Sir Mark Elder’s Farewell to the Hallé at the Proms

8pm, BBC Four

A testimonial for the 77-year-old music director of the Hallé symphony orchestra in Manchester, who is retiring after 25 years in post. Mahler’s muscular Symphony No 5 is preceded by Timotheus, Bacchus and Cecilia, a recent James MacMillan composition here bolstered by the Hallé youth choirs that have become part of Elder’s legacy. Graeme Virtue

The Jetty

9pm, BBC One

As detective Ember Manning (Jenna Coleman) investigates violence against teenage girls, this twisty thriller never lets us forget that she was once a teenage girl too. Now the discovery of a body in the lake is pushing Ember to confront the unthinkable about her own past vulnerability and the present vulnerability of her daughter. Ellen E Jones

Ibiza Narcos

9pm, Sky Documentaries

The drug series reaches its conclusion, with infighting and violence dominating the cocaine business of the early 2000s. It’s a far cry from hippy Ibiza, with more modern hedonism tempered by graphic scenes of blood, gore and a lost eye. And the dealers remain without sympathy for the customers who overdosed or became addicted. Hannah Verdie r

The Turkish Detective

10pm, BBC Two

Just when you think you’ve had every permutation of serial killer, this Istanbul-set procedural comes up with a new one: a prolific murderer seemingly targeting refuse collectors. Will the detective’s leads turn out to be a load of old rubbish? We’ll have to wait and see but, either way, at least you can’t accuse this plot of being recycled. Alexi Duggins

Film choice

Free Guy, 9pm, Film4

They are collaborating on the new Deadpool film, but actor Ryan Reynolds and director Shawn Levy first joined forces for this effortlessly enjoyable comedy thriller. Reynolds plays Guy, an NPC (non-playable character) in a GTA-style video game who develops self-awareness when he falls for the avatar of Jodie Comer’s Millie – her programmer is surreptitiously exploring his virtual world to try to prove her AI code was stolen. There’s a lot of fun had ribbing gaming culture – the overgrown kids who participate, the gratuitous violence, the inept players (keep on eye on the background for some choice examples) – while Reynolds’s innate charm and wit keep it all running smoothly. Simon Wardell

Live sport

All Ireland Hurling: Clare v Cork, 3pm, BBC Two The final at Croke Park.