“Sir?” The desk sergeant held his hand over the phone. “You may want to take this before you go. It’s forensics, they’ve made a mistake with the bones.”

Corstorphine pointed towards his office, grabbing his phone as the call was routed through.

“Corstorphine. What have you got?”

“Afternoon, Inspector. We’ve had the report back from the DNA lab. Those bones you asked us to test, they weren’t cattle as originally thought. They’re human.”

He sat in stunned silence for a few seconds as the enormity of the words hit home. “Human! How can you make such a basic mistake?”

“The bones had been carved. Our first diagnosis is made on bone shape. Any technician here will recognise human skeletal bones. It becomes a lot more complicated when the bones have been worked like this. We shouldn’t have let the report go out to you without confirmation from the DNA analysis, but one of our junior technicians was overly anxious to give you something as soon as possible.”

Corstorphine swore under his breath, the day was going from bad to worse. “What can you tell me about the bones? Are they from the same individual?”

“They come from five individuals. The finger bone we collected yesterday evening from the lock in the laird’s cold store was the first indication that we were dealing with human remains. That’s what made me chase up the DNA results in the first place, get them to fast track the tests.”

“Jesus, so we have a serial murderer who carves his victims’ bones to make traps for new victims?”

“Not necessarily. The bones date to around twenty years ago. Another thing you should know, they’re all children’s bones. None of the skeletons had reached beyond puberty. I’m having the report finished now. You should receive it in your inbox by close of play today.”

“OK. Thanks.” Corstorphine spoke distractedly, his mind whirling at the ramifications of what had just been said.

“Sorry we let you down on the initial findings.”

Corstorphine muttered an acknowledgement and grabbed his coat. “Hamish, you hold the fort. Frankie will be back in an hour or so. Bill, you come with me.”