PH was following the " Bible John " case where 3 young women were murdered in Glasgow,and there was a sick theme connected to the murders which was that the 3 young women were menstruating.
PH was convinced that the murderer was an ex-cop,but I have my doubts whether the man who was arrested in the end,was ever a cop,and that was Peter Tobin.
PH wrote a book based on the killings " Dancing with the Devil " because the 3 women had been murdered after attending a dance hall in Glasgow.