After 93 well-lived years, Violet MacAskill is ready to simplify her life. Her eccentric solution? She'll throw a decanting and decluttering party at her family home--a Scottish Baronial manor near the seaside town of Inversgail, Scotland. Violet sets aside everything she wants or needs, then she invites her many friends in to sip sherry and help themselves to whatever they want from all that's left.

Janet Marsh and Christine Robertson, two of the women who own Yon Bonnie Books in Inversgail, enjoy themselves at the party. Not everyone who attends has a good time, though. Wendy Erskine, director of the Inversgail museum, is found dead, and rumors swirl about food poisoning from a local food truck. Then Violet tells Constable Hobbs that a tin of rat poison is missing. And when Hobbs' own grandmother comes under suspicion for murder, he enlists the women from Yon Bonnie Books, and the race is on to find the murderer.

But where do they begin? Are there clues in the "Shocking Stockings" exhibit at the museum? Will the antique scrapbook pasted full of trivia about arsenic and bygone poisoners offer a solution? Or does the answer lie closer to home--is one of Violet's friends truly toxic? Poisonous games are afoot in Inversgail and the women of Yon Bonnie Books are playing to win.