Delusion in Death by J D Robb
It was just another after-work happy hour at a bar downtown--until the madness descended. And after twelve minutes of chaos and violence, more than eighty people lay dead.
Lieutenant Eve Dallas is trying to sort out the inexplicable events. Surviving witnesses talk about seeing things--monsters and swarms of bees. They describe sudden, overwhelming feelings of fear and rage and paranoia. When forensics makes its report, the mass delusions make more sense: it appears the bar patrons were exposed to a cocktail of chemicals and illegal drugs that could drive anyone into temporary insanity--if not kill them outright.
But that doesn't explain who would unleash such horror--or why. Eve's husband, Roarke, happens to own the bar, but he's convinced the attack wasn't directed at him. It's bigger than that. And if Eve can't figure it out fast, it could happen again, anytime, anywhere. Because it's airborne...