The winds of change have brought great joy to Lady Arianna and Saybrook, who have recently welcomed an infant son to their family. They are still adjusting to their new life when a letter arrives from Arianna's dearest friend and former comrade-in-chicanery inviting them to a gala fiftieth birthday celebration in Switzerland. With the blessing of their surgeon friend, they decide to make the trip, only to find themselves once again drawn into a dangerous web of political intrigue that may ignite war throughout Europe.

However, once in Geneva, Arianna and Saybrook learn that her half-brother is missing and feared dead while on a clandestine government mission to Greece, where revolutionary fervor is rising against the rule of the Ottoman Empire. What to do? They are saved from having to make an agonizing choice when their friends offer to care for their son while they undertake the perilous journey to learn the truth . . .

But Truth proves dauntingly difficult to unravel. Nothing is as it seems, leaving Arianna and Saybrook uncertain of whom to trust as they seek to help the British government prevent war from breaking out in the region. And when explosives go missing from the armory atop the Acropolis, they are in a race against time, with their lives hanging in the balance . . .