Necklace and Calabash by Robert Van Gulik

Judge Dee's fishing vacation plans are suddenly shattered when the inn cashier is found slain in a river. When he is summoned to the Emperor's palace to find the princess's stolen pearl necklace, he wonders: could the theft be connected to the cashier's death? And what of Master Gourd and the sinister Lang Liu? Only the master detective of ancient China can come to grips with the tangled mystery of Necklace and Calabash.