The Golden Dragon. The Maintenon Mysteries, #7

Opera star Largo Banzini is killed by a dart from a blowgun at the end of Act One of The Golden Dragon. It's an impossible crime, and Inspector Gilles Maintenon, who lost his wife Ann only a short time ago, has been a bit off lately. They have two thousand witnesses, all kinds of political pressure, too many people with some kind of a motive, and not enough real information. He's also a pretty good teacher, and the bright young Constable Louis Bedard has been assigned to the case.
Somebody sees something in this young man, who has enough seniority to write the sergeant's exam. He has ideas, if only he can overcome a basic shyness. If he does well, there's no need to go back to traffic duties and foot patrols. This is the seventh volume in The Inspector Gilles Maintenon Mystery Series.