Frederique Murcheson's introduction into society hasn't gone smoothly--some would even call it a disaster. Only Freddie considers her debut a success. Her scheme to become a makesmith has gone off flawlessly. The only thing that could upset her plans now would be if someone discovered that brilliant tinker Fred Merchant is, in fact, a lady in disguise.

Wooing a spoiled heiress is not exactly Barnabas Smith-Grenville's idea of high espionage. However, considering his brother disappeared on the job, supposedly into the most iniquitous of opium dens, he cannot expect much better. At least the assignment will afford him time to search for his brother, whom he suspects is in spy-related trouble rather than a drug-addled haze.

But when Freddie proves to be both irresistible and the key to the answers he seeks, Barnabas finds himself not only entwined in a scandalous mystery involving lethal submersibles and deranged dirigibles, but also in a dangerous game of the heart...