Our Heroine is a globetrotter with a book in the works, a travel guide for ladies. She is deeply concerned that the negative publicity will scupper her efforts to get published. Our Hero shows up and they devise a fake engagement and convince the guy from the Yard to let them help with the investigation. So the foursome (Our Hero, Our Heroine, her sister, and the Inspector/love interest for sis) poke around to identify the perpetrators of the attack on Our Hero (Russian foreign agents trying to get hold of a solar powered cannon, or at least the plans for same) and the identity of the Bridegroom. There's also a disgruntled ex-lover of Our Hero in the background. Everything ties up _very_ neatly. Throughout, Our Heroine deploys her tessen, a Japanese battle fan. This is pretty awesome and highly reminiscent of some of Tamora Pierce's books.
I read a lot of this author under her various names. This isn't a bad entry -- it has a couple of nerds getting together, which is always a good thing. Also, he tells her that sometimes she clanks, which is high realism, given all the stuff she carts around with her, and as a former occasional D&D player, I am all over the clanking.