It’s 1923, and Paris is beginning to recover from the ravages of World War I and the Spanish flu epidemic. Naïve young American Muriel Ross stumbles into a plum assignment photographing antiques for a globetrotting US senator. But events take a dangerous turn when she discovers that her employer is on a mission far more momentous—and potentially deadly—than a mere shopping trip. Soon, Muriel is enmeshed in a covert alliance dedicated to authenticating a fragment of the True Cross—and protecting it from those who will stop at nothing to steal and discredit it.