Fianna Fitzmichael is hopelessly in love with Jamie Rooney. So when he mysteriously vanishes, she’s beside herself. Hoping a visit to her sister in London will put her broken heart on the mend, Fianna catches a train—and the unwelcome attention of a lecherous man. Though a kind university student named Neill McBride comes to her rescue, the headstrong Fianna still falls prey to a mob of Gypsies who steal her luggage and abandon her by the cave of Crazy Nan, a self-professed witch.

But the strangest leg of her journey comes when Fianna overhears Crazy Nan talking to members of the Irish Republican Brotherhood—including her Jamie. The brotherhood doesn’t take kindly to interlopers, though, and suspect Fianna is an undercover agent for the British. To prove her loyalty to Ireland, Fianna embarks on a perilous mission that plunges her deep into political conspiracies and treacherous secrets. She seems to have a guardian angel in the dashing, enigmatic Neill, but can even he keep her safe as the danger mounts?