Moors Murders: The Witness

Channel 4, 9pm

Between 1963 and 1965, Ian Brady and Myra Hindley (right) murdered five children aged ten to 17 after sexually assaulting them, disposing of their bodies on the moors near Manchester.

Even now the killings remain perhaps the most notorious crimes in modern British history, and this three-part series uses previously unseen letters from Brady and Hindley to retell the story and attempt to understand their capacity for pure evil.

In the opening episode former pop star Janie Jones looks back to the relationship she struck up with Hindley while she was in prison. It ended after Jones realised she was mistaken in thinking that Hindley's role in the murders had been overstated.

Commentators include journalist Clive Entwistle, who knew Hindley and saw the police investigation, and criminologist Professor David Wilson. ★★★★☆