Two unlikely detectives. A killer cocktail of suspects.

A Gibson martini garnished with three silverskin onions is 77-year-old Mimi's favourite cocktail. It is best served with a crossword puzzle, not as an apéritif at Jane Ireland's extravagant auction party.

But given Mimi has been blackmailed into attending Jane's event, at a grand old mansion on Mackinac Island (Michigan's answer to The Hamptons), there are worse drinks she could spend an evening sinking.

Thankfully for her, she's roped her granddaughter, Addie - who is escaping the heartache caused by her manipulative ex-fiancé - into accompanying her. While Addie spots celebrities and socialites in the manor's labyrinth of dark rooms and Mimi wonders how to confess the real reason for her presence at the soiree, a scream pierces the air.

Jane is dead.

And when a second body turns up, Mimi and Addie soon become the unlikeliest of sleuths in a race to narrow down the suspects.

In a house that contains as many secrets as the people within it, it's going to take more than a Gibson to survive the night…