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 aperitif 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-fiance - 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...

Praise for THIS IS NOT A GAME:

'Agatha Christie brought bang up to date in this innovative and funny spin on the classic country house murder. I adored Mullen's intrepid sleuthing duo and loved unravelling this locked-room mystery with them' Clare Mackintosh

'Miss Marple meets Only Murders in the Building, this is a proper old school murder mystery brought bang up to date by Kelly. Entertaining from start to finish' Jennie Godfrey

'A zippy, witty and delightful game of twists, featuring a wonderful new puzzle-solving duo guaranteed to win your heart' Chris Chibnall

'Mullen's debut introduces us to a sparkling new crime-fighting partnership: acerbic septuagenarian Mimi and her smart-as-a-whip granddaughter, Addie. In This Is Not A Game, the pair find themselves trapped together on an island mansion as murders ensue. Crackles with wit and cosy crime goodness' Vaseem Khan