Is apparently this book, No. 17 in King’s Sherlock Holmes + Mary Russell mysteries.
Self knows she needs to come clean: She could not read to the end of All the Frequent Troubles of Our Days. She could not read past the Russians belligerently recruiting Arvid Harnack (while Mildred is out of town, in Copenhagen — but could she have made a difference? But could the Russians have been a little less showy with their knocking on the Harnacks’ door with not the slightest compunction about informants? After all the trouble the Heaths took to have their 11-year-old disguise the Harnacks’ activities! Self couldn’t stand those Russian thugs.)
Anyhoo, Castle Shade reads fresh. She can’t believe it’s the 17th in a series. She confesses that, in the beginning, she found the idea of a married Sherlock Holmes a little far-fetched, but once she started reading, she found the scenes between MR and SH very crisp. Story’s got a fascinating setting, too: it starts on a train headed to Dracula’s castle! Yes, that’s right: the intrepid pair are headed to Romania. Oooh! Stay tuned.