Kerry Greenwood

Murder in the Dark Kerry Greenwood Reissue edition

Itas Christmas, and Phryne has an invitation to the Last Best party of 1928, a four-day extravaganza being held at Werribee Manor house and grounds by the Golden Twins, Isabella and Gerald Templar. She knew them in Paris, where they caused a sensation.
Phryne is in two minds about going. But when threats begin arriving in the mail, she promptly decides to accept the invitation. No one tells Phryne Fisher what to do.
At the Manor House, she is accommodated in the Iris room, and at the party dallies with two polo-playing women, a Goat lady (and goat), a large number of glamorous young men, and a very rude child called Tarquin.
The acolytes of the golden twins are smoking hashish and dreaming. The jazz is as hot as the drinks are cold. Heaven. It all seems like good clean fun until three people are kidnapped, one of them the abominable child, and Phryne must puzzle her way through the cryptic clues of the scavenger hunt to retrieve the hostages and save the party from further disaster.