From the moment Hollis Darby meets Ana Newport, he's smitten. Even though he's from a wealthy, established family and she isn't, he wishes he could have a life with her by his side. But Hollis has a secret: the deep coffers that have kept his family afloat for generations are bare, so he supports himself by writing penny dreadfuls under a pseudonym. If not for the income from his novels, he would be broke.

Ana Newport also has a secret. Though she once had a place in society thanks to her father's business, bankruptcy and scandal reduced the family fortune to nothing more than a crumbling town house. So Ana teaches music during the day, and at night she assumes the identity of the "Phantom Fox." She breaks into the homes of the wealthy to reclaim treasures she feels were unjustly stolen from her family when they were struggling.

When Hollis's brother needs to hire a music tutor for his daughter, Hollis recommends Ana, giving him a chance to spend time with her. Ana needs the income and is eager for the opportunity to get to know the enigmatic gentleman. What neither of them expects is how difficult it will be to keep their respective secrets from each other.

When a spree of robberies rocks the city, Ana and Hollis join forces to solve the crimes, but working together deepens the affection between them. After all, who better to save the day than a gentleman and a thief?