Doors open at 7. The sacrifice is at 9. The dress code is, as usual, black tie.

It's the winter solstice in a Philadelphia that has been eroded by extreme weather, economic collapse, and disease-carrying mosquitoes. The Saturnalia carnival is about to begin, an evening on which reality is suspended, and troubles forgotten.

For tarot reader Nina, Saturnalia is simply a cruel reminder of the night that changed everything for her - the night she walked away from the elite Saturn Club, with its genteel debauchery, arcane pecking order, and winking interest in alchemy and the occult.

But when she gets a chance call from Max, her last remaining friend from the Saturn Club, Nina will put on a dress of blackest black and attend the Club's wild solstice masquerade, the biggest party of the year, on a mysterious errand she can't refuse.

Before the night is over, she will become the custodian of a horrifying secret - and prey to a mysterious hunter.