GLITTERING DEATH... 1793: French revolutionaries lop off the beautiful, if rather vacant, head of Queen Marie Antoinette. They claim the Queen squandered France's treasury to buy a sumptuous diamond necklace. Fast forward to the present: Vancouver history buff Ailie Mooney, 14, inherits from her eccentric great-uncle a packet of Marie Antoinette's letters - and a clue to the whereabouts of the infamous necklace's central stone, a.k.a., the Midnight-Blue Marble. There's a multi-carat problem, though. Someone wants to fi gure out the clue before Ailie does. Using Marie Antoinette's letters, our determined, if perpetually disorganized, sleuth must hunt down the diamond before she becomes the next murder victim in its ever-bloody saga.