Corstorphine nodded slowly, his eyes fixed on the wooden plaque. The children would have been buried twenty years ago, but somebody had dug them up within the last year – to take the bones or make it easier to find the remains? At least the motive was now unassailable. But how many other people were involved and how in God’s name was he supposed to track them down before the murderer got to them first? He thanked Lamb’s father before excusing himself, returning the call to the forensics department at Inverness.

“Corstorphine here again. I need a team here asap. We have potentially five children’s graves to examine in the old orphanage gardens. I’ll text you through the location now. You’ll have to bring back-up to protect the site. The press are here in force and our team is too thinly stretched as it is.”

He stood looking at the oak sapling and its message in silent contemplation. Whoever the murderer was, it was someone who felt no compunction about digging up five children’s graves and removing their bones to carve into killing mechanisms. What sort of person was even capable of such an act? Were the bones selected as some twisted tribute? A belated memorial to each dead child? Corstorphine left the two constables looking after the orphanage garden site and returned to the station. Events had moved so fast, he’d hardly had a chance to think, with one thing tripping over the heels of the next.

“Are our guests still in the cells?”

Hamish shook his head before replying in his languorous way. “No, sir. Once the reporters had cleared off, they decided it was time to go.” He looked momentarily flustered, “Did you want me to keep them here, sir? I thought they were free to come and go as they pleased?”

“No, it’s OK, Hamish. They weren’t under arrest.” He couldn’t think of anything else to ask them even if they had still been waiting in the cells. A chilling thought had just occurred to him even as he spoke to the sergeant. “Pass me the evidence locker key, Hamish. I didn’t get a good look at the weapon before I bagged it.”

The key was handed over and he retrieved the gun in its plastic evidence bag, turning it over to reveal an inscription carved into the wooden stock. The writing was in the same flowing script he’d seen written on the hourglass and plaque. He read it with some difficulty through the plastic cover.

You’ll know when it’s time.