There's a new documentary coming to BBC and it could be 'the best true crime documentary ever made'.
The Hunt for Bible John originally aired on BBC Scotland last year, but is now available on BBC iPlayer after airing on telly earlier this week.
You can watch the trailer below:
The doc investigates the unsolved murders of three women in Glasgow in the sixties, speaking to a team of experts - including criminologists and forensic psychologists - who will give their views on the cases.
Bible John is responsible for the deaths of Patricia Docker, 25, Jemima MacDonald, 32, and Helen Puttock, 29 - but his identity still remains a mystery. The documentary also delves into how the killer managed to evade justice and escape police investigations.
The unusual moniker 'Bible John' emerged after a witness described him as quoting extensively from the Old Testament. But despite witnesses, the murders have never been officially solved.
Some think that Bible John could actually be Peter Tobin, who was jailed for murder in 2007 - however, this has never been proved.
Following the documentary airing, many have been praising the two-part series as being one of the best they've ever seen.
A review in the Guardian asked 'is this the best true-crime documentary ever made?'
And viewers on Twitter certainly think so, with one writing: "The Hunt for Bible John really is an excellent bit of TV. Definitely recommended viewing."
While another added: "Just finished watching The Hunt for Bible John on catch up. That is some incredible documentary making. Absolutely riveting."
A third said: "The Hunt For Bible John is a phenomenal piece of work."
And a fourth said: "‘The Hunt for Bible John’ on BBC Scotland is excellent. Also a brilliant social history of Glasgow. Recommend!"
You can watch The Hunt for Bible John on BBC iPlayer now.