Death before wicket : a Phryne Fisher mystery / Kerry Greenwood.

Enhanced descriptions from Syndetics:

Phryne Fisher is on holiday. She means to take the train to Sydney (where the harbour bridge is being built), go to a few cricket matches, dine with the Chancellor of the university, and perhaps go to the Arts Ball with that young modernist, Chas Nutall. She has the costume of a lifetime, and she's not afraid to use it.

When she arrives there, however, her maid Dot finds that her extremely respectable married sister Joan has vanished, leaving her small children to the neglectful care of a resentful husband. What has become of Joan, who would never leave her babies? Surely she hasn't run away with a lover, as gossip suggests?

Then while Phryne is visiting the university, the very pretty Joss and Clarence ask her to find out who has broken into the Dean's safe and stolen a number of things, including the Dean's wife's garnets and an irreplaceable illuminated book called the Hours of Juana the Mad. An innocent student has been blamed.

So Phryne girds up her loins, loads her pearl-handled .32 Beretta, and sallies forth to find mayhem, murder, black magic, and perhaps a really good cocktail before more crime erupts in Sydney.