Murder on a Midsummer Night (Phryne Fisher Series #17)

The Hon. Phryne Fisher, languid and slightly bored at the start of 1929, has been engaged to find out if the antique-shop-owning son of a Pre-Raphaelite model has died by homicide or suicide. He had some strange friends—a Balkan adventuress, a dilettante with a penchant for antiquities, a Classics professor, a medium, and a mysterious supplier who arrives after dark on a motorbike. Simultaneously, she is asked to discover the fate of the lost illegitimate child of a rich old lady, to the evident dislike of the remaining relatives.

With the help of her sister Beth, the cab drivers Bert and Cec, and even her two adoptive daughters, Phryne follows eerie leads that bring her face-to-face with the conquest of Jerusalem by General Allenby and the Australian Light Horse, kif smokers, spirit guides, pirate treasure maps, and ghosts.