One moment Isla Crawford is inside McQuivey's Costume Shop trying on a Jacobean-style gown for the parliamentary Autumn Ball, and the next, she has inexplicably traveled back to 1605, mere weeks before the culmination of Guy Fawkes's infamous Gunpowder Plot.

Simon Hartworth, Lord Bancroft, finds a mysterious woman on his sister's doorstep during a storm. intrigued by the stranger's quirks and bewildering speech, Simon is drawn into Isla's belief that there is a dangerous plot against Parliament.

Isla and Simon must race to unravel the threads of the treasonous plan even as they wonder how their hearts will navigate their deepening connection and the seemingly insurmountable four centuries that separate their lives.