In the crowded, smoke-filled Barrowland Ballroom of 1960s Glasgow, a polite, well-dressed man quoted scripture about adulterous women being stoned to death. Hours later, his dance partner was dead. He became known as Bible John, and he was never found.

This episode investigates one of Scotland's most haunting unsolved cases, the murders of three young mothers between 1968 and 1969. We trace the groundbreaking manhunt, the surviving witness who came face to face with the killer, and the unsettling theory that police may have chased a single phantom while real killers walked free.

• How the predator used the bustling over-25s nights at the Barrowland as camouflage to stalk vulnerable, often estranged mothers
• The chilling 20-minute taxi ride in which witness Jean Langford captured a detailed profile of the killer down to his o ...