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'What did you do?! Did you touch it?' she shouted at him over the noise. Jack shook his head, rooted to the spot and looking very pale.When the valuable Koh-i-Noor diamond vanishes in mysterious circumstances during their school trip, Emmie and Jack must navigate thieves and deception in Victorian London to discover what has happened to it.Soon it becomes clear that the fate of the upcoming coronation rests in their hands - will they find the diamond and their way back in time?