The Body in the Tower is the second Agency book; A Spy in the House is the first. You've been warned.
In A Spy in the House, Mary Quinn went undercover as a housemaid. In the sequel, The Body in the Tower, her job is even harder, and she must disguise herself as a young boy in order to investigate a mysterious death at a building site. Mary commits fully to her investigation; she cuts off her hair and takes up residence in a boarding house, where she is forced to share her quarters with a strange man. But when an old friend also starts working on the building site, Mary's secret is that much harder to keep. Can she solve the mystery and keep her identity a secret?
The books in this series are great mysteries, and they're filled with lots of historical details without boring the reader. Mary's job as a spy takes her to all different walks of life, so readers learn about both wealthy and poor residents of Victorian England, and the details are gruesome enough to appeal to today's teens. The romance also continues to develop nicely, and I honestly can't guess what's going to happen next. I'm eagerly awaiting the third book to find out, and I hope there are many more Mary Quinn mysteries after that.