"The Debutante's Code" by Erica Vetsch - Thorndyke & Swann Regency Mysteries, book 1

Newly returned from finishing school, Lady Juliette Thorndike is ready to debut in London society. Due to her years away at school, she hasn't spent much time with her parents, and sees them only as the flighty, dilettante couple the other nobles love. But when they disappear, she discovers she never really knew them at all. They've been living double lives as government spies--and they're only the latest in a family legacy of espionage. Now Lady Juliette is determined to continue their work. Mentored by her uncle, she plunges into the dangerous world of spy craft. From the glittering ballrooms of London to the fox hunts of country high society, she must chase down hidden clues, solve the mysterious code her parents left behind, and stay out of danger. All the while, she has to keep her endeavors a secret from her best friend and her suitors--not to mention handsome Bow Street runner Daniel Swann, who suspects her of a daring theft. Can Lady Juliette outwit her enemies and complete her parents' last mission? Or will it lead her to a terrible end?

I enjoyed that this book is a set-up for a series about Juliette and Daniel, not just a stand-alone. This is Juliette's introduction to the spy world, and it's a lot to take in for a debutante freshly home from abroad. She's no only navigating her first season, being on hand to support her best friend, and after years abroad at school, STILL not getting to see her beloved parents, but also doing nightly cryptography work, spy training, art theft, and being hounded by a handsome Bow Street Runner. She's got a pretty full plate.

It was fun to Daniel come into his own as he fights for his place among the Bow Street Runners. Lots of mystery remains about his past and anonymous patron. I'm glad we get more books to get to know him! And I have to say, I adored Uncle Bertie. I hope we get more of him in the future! I'm looking forward to the next book and what exciting mystery will cross over between the criminal underworld and international espionage--and toss Juliette and Daniel back together.

Thorndyke & Swann Regency Mysteries
1. The Debutante's Code
2. Millstone of Doubt 
3. Children of the Shadows