I love this series. I've been following Helen Hawthorne's adventures since she first appeared in 2003 in Shop Til You Drop. The settings are always fun and well researched, and the characters - Phil, Margery, Peggy, and Pete the Parrot, along with numerous less permanent visitors, continue to hold my interest.
In Checked Out, Helen goes undercover as a volunteer at a small, upscale library, searching for a John Singer Sargent water color ("Muddy Alligators," signed on the back by Clark Gable, who lost it in a poker game in 1924) accidentally left in a donated book--somewhere in 300 boxes of books. And there appears to be a ghost, or at least a squatter, hiding in the library. Meanwhile, Phil is courting sunburn as an undercover gardener, Peggy is worried about Pete's personal life, and the new tenant at the Coronado Tropic Apartments is showing off his mojitos.
If you enjoy humorous mystery, you can't do better than Elaine Viets.