Calum McCallum was a disc jockey at a local Edinburgh Radio station, hosting a show that started at 8.30pm involving music and phone in features. However he was also secretly involved in an underground dog fighting group, and went to many of the fights.
Early in 1990, McCallum began a relationship with DI Gill Templer, keeping from her his interest in illegal dog fighting. However several months later an operation by the police and SSPCA raided a fight in Dunfermline and McCallum was arrested. Fearing for his chances in court, McCallum tried to buy his way out of jail with information he had acquired in his friendships through his celebrity status. He had heard about Hyde's, a club within a club where the wealthy paid to watch male prostitutes fight each other in an underground boxing ring. He had also heard that John Rebus was investigating a murder connected to the club, so when he met with Gill Templer he asked to speak to Rebus (after Gill informed him their relationship was over). He told Rebus all he knew, detailing how to find the club and the sorts of goings-on that happened there. Although Rebus promised to help him, it is unknown what became of McCallum.