S2, E1: Since the 1950s experts have remained baffled by a jumble of human bones discovered in a unique series of caves on the North York Moors. Known as the ‘Windy Pits’, due to the air which gusts out of the mouths of these caves, this area has been the inspiration for much folklore and mystery for thousands of years. Human and animal remains thought to date right back to prehistoric times have been excavated from the caves but one discovery in particular stands out; one cave, called Slip Gill, where the tangle of bones might belong to a male, female and two adolescents. Now the history cold case team hopes that by throwing the full arsenal of forensic tests combined with up to date historical research at the mystery could finally get some concrete answers. Is this a family of people we are looking at in Slip Gill and, if so, what is a family doing dead at the bottom of a cave in Yorkshire? The trail is set to take us into a dark world of ritual sacrifice, and right back to the limits of British recorded history.