Rhona lifted her head from the microscope. A smirr of rain was touching the window, but here and there the sun was breaking through the cloudy skies. The park below the laboratory was quiet, just a few mums and kids at the swings and a couple walking, arm in arm. As she watched, the boy stopped beside a clump of trees, bent down and picked a bluebell and handed it to the girl. They began to kiss.

Six months before, Rhona had stepped over another yellow tape just where the couple were standing now. It had turned out to be a student, murdered on his way home from a dance at the Students’ Union. Last night’s murder, she thought, made four in one year. All young men.

The first two had been violent assaults with no evidence of sexual activity, but the one in the park had been different. It had all the hallmarks of queer bashing. The student was gay and was in a known cruising area. His chest and arms were covered with kick marks and his head had been caved in by a blunt instrument, which was never found. The area had been scoured for traces of the killer – or killers. It had been useless. Heavy overnight rain had washed the place clean of clues.

One thing connected that murder to this one. The victim had been wearing a thin leather neck band with a Celtic cross on it. At the post mortem the pathologist had found bruising round the neck, consistent with the neck band being pulled during the assault. What if tightening the neck band had been part of a violent sexual assault?

When Sean found out what her job was, he had laughingly called her Lady Death. Rhona didn’t care. She loved her work. She loved the functions and the structures and the painstaking carefulness of it all. She had forsaken medicine because she found it too depressing. So many sick people and, if she was honest, so little she could do to help them. Forensic Science was different. Here she could help, as long as she was prepared to look for the truth. That was the fascination. The truth hid from her, until she found just the right question to ask. At the end of the day, it wasn’t what had happened but why it had happened that held the truth.

Maybe that’s why we couldn’t find the killer, she thought. Maybe we got the ‘why’ bit of the jigsaw wrong.

The couple had moved off towards the Art Gallery and were climbing the steps to get under the ornate portico, out of the rain. Rhona went back to the microscope, not wanting to think about the Gallery. Not since last Friday when she’d taken her lunch there and spotted the familiar long blue raincoat and dark hair.

She tried to concentrate on the next slide, ignoring the knot in her stomach.

‘Fancy coming out for some lunch?’ Chrissy was standing in the doorway.