For nearly 300 years, the mysterious journal of Jacobite exile Mary Dundas has lain unread — its secrets safe from prying eyes. Now, amateur codebreaker Sara Thomas has been hired by a once-famous historian to crack the journal's cipher. But when she arrives in Paris, Sara finds herself besieged by complications from all sides: the journal's reclusive owner, her charming Parisian neighbor, and Mary, whose journal doesn't hold the secrets Sara expects.
It turns out that Mary Dundas wasn’t keeping a record of everyday life, but a first-hand account of her part in a dangerous intrigue. In the first wintry months of 1732, with a scandal gaining steam in London, driving many into bankruptcy and ruin, the man accused of being at its center is concealed among the Jacobites in Paris, with Mary posing as his sister to aid his disguise.
When their location is betrayed, they’re forced to put a desperate plan in action, heading south along the road to Rome, protected by the enigmatic Highlander Hugh MacPherson.
As Mary's tale grows more and more dire, Sara, too, must carefully choose which turning to take... to find the road that will lead her safely home.