The Village Library Demon-Hunting Society by C. M. Waggoner

A librarian with a knack for solving murders realizes there is something decidedly supernatural afoot in her little town in this cozy fantasy mystery.

Librarian Sherry Pinkwhistle keeps finding bodies—and solving murders. But she's concerned by just how many killers she's had to track down in her quaint village. None of her neighbors seem surprised by the rising body count...but Sherry is becoming convinced that whatever has been causing these deaths is unnatural.

When someone close to Sherry ends up dead, and her cat, Lord Thomas Crowell, becomes possessed by what seems to be an ancient demon, Sherry begins to think she’s going to need to become an exorcist as well as an amateur sleuth. With the help of her town's new priest, and an assortment of friends who dub themselves the "Demon-Hunting Society," Sherry will have to solve the murder and get rid of a demon.

This riotous mix of Buffy the Vampire Slayer and Murder, She Wrote is a lesson for demons and murderers alike: Never mess with a librarian.