This book is set in the 1920's. The main character, Phryne Fisher, is a "jazz baby" from the wrong side of the tracks. Born and raised dirt poor in Australia, her family comes into an English title when previous heirs die. Now living the life of the idle rich, she's not quite sure what to do with herself. She is approached by a family who fear that a daughter in Australia is being poisoned by her husband. Phryne thinks it might be "fun" to see what she can find out.
There are a number of books in the series. They are short, but (based on this first one) pack a lot of charm and character development into a small space. Highly recommended - and I can't wait to dig into the next one (after I pick it up, of course!).