The book begins with a prologue from 1867 in which the three young Harrington brothers explore their attic searching old boxes for hidden treasure.  In keeping with their family’s heritage of smuggling artifacts—or at least acquiring them under questionable circumstances—they make a pact to stand together throughout their lives as brothers and adventurers.

The actual story begins 18 years later when the brothers—now grown men—attend a dull party hosted by their mother.  The youngest brother, Nathanial, meets a beautiful woman who seems strangely familiar.  They flirt and she flees, until he later finds her in the library—a highly unusual place for a party guest to be lurking.  When she disappears again, Nate knows she will someday reappear in his life.

Within the next 24 hours Gabriella Montini returns to his house, this time in the middle of the night.  She boldly breaks into his home to search the library for her dead brother’s stolen seal.  This ancient artifact mysteriously vanished when her brother (also mysteriously) died while searching for lost treasures.  Orphaned and now completely alone, Gabriella hopes to restore her brother’s "good" name by reclaiming the seal from whoever stole it. And to her, the most likely suspects are the adventurous Harrington brothers.

When the family catches her in the act, they listen to her story and decide to help her rather than turn her in to the authorities.  However, Gabriella finds that living under the same roof as the handsome and charming Nate poses a problem for her.  When he also proves himself to be a loyal friend and helpful business partner, she finds herself caught up between her desire for him and her desire to find out the truth about her brother.

Although the title refers to the lost seal and treasure associated with it, The Virgin’s Secret also alludes to the many lies that Gabriella tells Nate along the way, including the mystery around her own loss of virginity.  While this historical romance creates intriguing characters, the details surrounding the treasure sometimes overshadow the budding relationship.  Delving more into Nate’s past, for example, might have been more interesting than the abundant details describing the adventures of Gabriella’s morally-challenged brother.