For Scarlett Parker, part of the fun of living in London is celebrating the British holidays, and she's excited to share her first Bonfire Night with her cousin Vivian Tremont. Invited to a posh party by their friend Harrison Wentworth, Scarlett and Viv decide to promote their hat shop, Mim's Whims, by donning a few of their more outrageous creations. The hats prove to be quite the conversation starters as the girls mix and mingle with the guests--never suspecting that one of them is a killer.

It's a cold, clear night, perfect for the British tradition of tossing a straw stuffed effigy of Guy Fawkes, traitor to the crown, onto the bonfire. But instead of a straw man, they realize in the heat of the moment that the would-be Guy Fawkes is actually Harrison's office rival and he's been murdered. Before the smoke has cleared, Harrison is the Metropolitan police's prime suspect, and Scarlett and Vivian must find the real homicidal hothead before their dear friend's life goes up in flames.