Detective dramas are as common as British rain, and it takes a special kind of series to part the clouds and shine through something worth watching. ITV’s record is sporadic in terms of quality – they’ll either provide a mystery that joins the nation, as Broadchurch did, or deliver an unoriginal piece of rubbish like Dark Heart.

But their latest investigation offers some hope, delving into the delicate truth of a real-life murder and the devastating circumstances that followed. Here’s everything we know about the series.

What’s the story of A Confession?

In 2011, the 22-year-old Sian O’Callaghan went missing in Swindon. DS Steve Fulcher was put in charge of the case, which involved a thousand police officers searching for O'Callaghan. Eventually, the taxi driver Christopher Halliwell was arrested… but not immediately taken to the police station.

Fulcher took Halliwell to a secluded castle and extracted a confession – not only to O’Callaghan’s murder, but also the murder of Becky Godden who’d disappeared in 2003. Breaking police procedure, Fulcher was forced to resign because of the controversy.

The six-part series from Oscar-nominated writer Jeff Pope (Stan & Ollie, Philomena) doesn’t simply tackle the manhunt, it’s about the implications of finding the killer in the ‘wrong’ way. Should coppers be allowed to bend the rules for a needed result, as long as the ends justify the means?

Who’s in the cast for A Confession?

Martin Freeman tackles the morally confusing Steve Fulcher. Freeman has been in the Marvel movies, the Hobbit movies, and the exceedingly popular Sherlock - so this is quite a departure.

Imelda Staunton (Downton Abbey) will play Karen Godden, the traumatised mother to Becky Godden.

Imelda Staunton stars as Karen Godden, whose daughter was murdered in 2003

Also starring in the series is Florence Howard (Dead Pixels) as Sian O’Callaghan, Siobhan Finneran (The Widow, Apostasy) as O’Callaghan’s mother Elaine, and Jo Absolom (Doc Martin) as the murderer Christopher Halliwell.

What's the A Confession release date?

An exact date hasn't be revealed yet, but A Confession will air sometime in August on ITV