In 1883 New York City, Mystere Rillieux is a toasted member of the Four Hundred, the elite of the city. Along with her Uncle Paul, she is able to bewitch those around her. Unknown to her social acquaintances, though, Mystere is actually the mysterious thief, Lady Moonlight, who has committed jewel thefts under the very noses of the wealthiest.
But railroad magnate, Rafael Belloch , is more than suspicious that Mystere is the masked woman that robbed him two years prior. When Rafe discovers that Mystere and her "uncle" aren't exactly who they appear to be, he must decide whether to expose them, even as he is powerless to stop his attraction to Mystere.