There have always been fairies in the world. It wasn't until toxic contamination along the Mississippi Delta mutated these secretive fey creatures into blood-sucking fiends that people became painfully aware of their existence.

Many people in the Louisiana bayou region died before people learned that fairy bites impart a poison that will either kill a victim or drive him insane. A lot of folks fled north, since the fairy population didn't seem inclined to migrate from its swampy environs. The rest remain ensconced in cities and towns protected by iron defenses that keep the mosquito-sized terrors at bay.

Annabelle Lee, the protagonist of Dead on the Delta, doesn't need to worry, however. A rare condition renders her blood poisonous to fairies, and her scent -- pleasant thought it may be to other humans -- keeps them at a safe distance. So Annabelle is one of the few who can work undisturbed in the bayou -- alligators, snakes and rednecks notwithstanding -- to track fairy movements and collect evidence to help in their study. And, when the need arises, she can wade unprotected into the swamp to assist police in homicide investigations.

The fairy problem is merely the backdrop to the story, the setting that sets Dead in the Delta apart from your more standard mystery novels. A little girl has been murdered, possibly in connection with a series of recent killings in the region, and neither the local police nor the FBI can pin down the killer.

Annabelle can help, given her unique ability to explore the swamps, where the illegal trade in a new designer drug -- derived from fairy poop and bleach, if you can believe it -- is making matters even more dangerous. But her help is greeted with some suspicion, given her addiction to alcohol and sleeping pills, her lackadaisical attitude toward deadlines and authority figures, her recent screwup on an assignment that might have left a woman for dead in the bayou, and her mixed-up relationship with the town's leading detective -- which is further complicated when her unresolved ex shows up leading the FBI investigation.

It doesn't help matters that one of her best friends is a prime suspect in the murder and another good friend has mysteriously fled town. You just know things will take a turn for the worse when she's assaulted by an invisible man....

This isn't the most nail-biting murder-mystery I've ever read, nor are the rabid fey exploited to their full potential. Annabelle herself is not the most likable protagonist, although she certainly has the potential to rise above her shortcomings. In any case, Jay has set the stage for future developments in this intriguing new world, and I am eager to explore this fairy-infested bayou with her and Annabelle further.