“I’m not surprised. Talk to the forensics team, they’re prioritising this case – you may be able to provide some assistance.” The phone went dead, leaving Corstorphine with the distinct impression that the DCI’s opinion of him had just dropped even lower than the subterranean point it had started from. At least forensics answered their phone with a cheerful tone, becoming even happier when they realised Corstorphine was on the other end of the line.

“Your murderer has been busy, taking out a lord this time!”

His murderer? Corstorphine hesitated, searching for the right words to let forensics know that the murderer was not someone he particularly wanted to claim as his own. The forensics guy filled the space for him.

“Gary won the sweepstake. His entry was Lord Lagan’s son – the MP, Reginald Lagan. Killed by the parliamentary mace. You have to admit that’s close.”

Corstorphine wondered at the psychology of finding enjoyment in predicting another’s death, especially before 7a.m. Perhaps that was what happened to you if you worked in forensics, a way of coping with the daily toil of death and injury. “What have you got on the murder method?”

“Ah, that’s why we thought of you. Whoever it was installed a syringe in the car headrest, activated by an electronic timer. Similar to your murders, but what really gave it away as your murderer was the bone case the electronics had been packed into. Quite a work of art, looks like it was milled in a machine shop. We’re running the DNA now. What’s the betting it comes back as one of your child skeletons?”

“What was in the syringe?” Corstorphine pressed for more information, anything that might give him the clue – any clue – to the murderer.

“Something pretty evil. Must be a neurotoxin of some kind to affect him that quickly, although having a dose injected straight into his neck wouldn’t have helped him any. It looks as if he managed to give himself a second dose when his hand went behind his neck, probably to check what had just stung him. It may take a while before we get any feedback on what’s left in the syringe; to be honest, we were all a bit wary of handling it.”

Corstorphine ran through the video footage in his mind. “I think the murderer swapped headrests. I saw her carry a small package to his car and fiddle about around the driving seat. She had thirty seconds at most.”

“She?”

“Yes, she. It looks like we’re dealing with a woman as far as the only video we have of the suspect shows. What about the poison, the neurotoxin? Any ideas where that could have come from?”

“Difficult to say without knowing what it is. It’s not the sort of thing you can buy over the counter at the chemists.”