“I’m convinced Roberts brought the jewellery here and hid it,” Sherlock Holmes said. “But where I cannot fathom at the moment.”

Dr Watson looked at the houses in front of him. They were standing together on a back road, which led to the rear of the properties. “Could he have accessed one of the houses?” he asked. “And hidden it somewhere out of sight of the servants?”

“That would be risky. There would always be the chance he’d been seen, if not by the servants of the household, then someone from one of the neighbouring houses.”

Watson laughed. “Perhaps he hid it in that pile of sand.” He pointed to a mound of sand clearly left by some builders prior to tackling a job.

“Not in the sand, no. But he might have dug a hole and hidden them underneath the sand. Look, there are traces of grains of sand here, nearby. I think he dug a hole, buried the jewellery, and then moved the pile of sand to cover it. After all, no-one notices the exact spot of a pile of sand.”

The Ferret poked his head out of Holmes’ coat pocket. “Shall I go and investigate?” he asked.

“Yes, that would be a good idea. It would be far too obvious if we were to start digging.”

Holmes put Ferret on the ground and he started to burrow his way into the sand. Holmes and Watson waited patiently. Occasionally they saw the surface of the sand ripple, but it wasn’t for nearly ten minutes before Ferret’s head popped up in the middle of the pile.

“I’ve found it,” Ferret said triumphantly. He looked around. “Oh. No, I haven’t.” His head disappeared again.

Watson shook his head. “We could be here for ages. I’ll be back shortly.”

He strode rapidly to the end of the back road and hailed a cab to take him to Baker Street. There, he hurried inside and up to their rooms. Shortly afterwards, he went back downstairs and took a second cab to rejoin Holmes.

“I have the solution,” he said.

He bent down and placed Poley the Moley on the edge of the sand pile. She immediately began digging and it wasn’t long before she was back.

“I’ve found the jewellery,” she said. “It’s just as Mr Holmes thought. Do you want me to go back and bring it out?”

“No, thank you,” Holmes said. “I’ll contact Lestrade and he can get his men to dig it up. In the meantime, I suggest we leave before we start to attract attention. Just one final thing, could you go back in and find Ferret, he seems to have got completely lost in there. Either that or he’s fallen asleep.”