Mississippi librarian Charlie Harris and his Maine Coon cat Diesel are on their guard. Oscar Reilly, the new director at the Athena College library, is on a mission to cut costs and has set his sights on the archive and rare book collection. Reilly's also out to replace Charlie's fiery friend Melba with someone younger, but his biggest offense is declaring all four-legged creatures banned from the stacks.

With enemies aplenty, the suspect list is long when Reilly's body is discovered in the library, but incriminating evidence throws suspicion on Melba. Charlie is convinced that his friend is no murderer, especially when he catches sight of a menacing stranger lurking around the library. Now he and Diesel will have to read between the lines, before Melba is shelved under "G" for guilty...