One moment, Isla Crawford is inside McQuivey's Costume Shop trying on a gown for the parliamentary Autumn Ball, and the next, she is standing in a garden, barefoot, coatless, and at the mercy of a fierce storm. Confused, she seeks refuge in a Tudor manor, where she discovers that she has traveled back to 1605, mere weeks before the culmination of Guy Fawkes's infamous Gunpowder Plot. With seemingly no way to get back home, Isla uses her twenty-first-century knowledge of the past to try to thwart Guy Fawkes and his coconspirators without altering the course of history forever.