What Song the Sirens Sang

Gideon Sable is suspicious when a stranger brings him a priceless magical stone for appraisal. Some treasures are more trouble than they''re worth. But before he can work out if he''s been set up, the stone is stolen from its impregnable hiding place. How? And why? Only one thing''s certain: no one steals from Gideon and gets away with it ...