The Black Circle: 06/25/13
The Black Circle by Patrick Carman is the fifth of the original 39 Clues series. Dan and Amy Cahill leave their au pair behind and fly solo to Russia. They are following the clues left by the mysterious NRR.
As with previous volumes, The Black Circle includes a hefty bit of E/I (though this one seems more caught up in rumor, than fact). Amy and Dan along with learning about the Lucians, also learn about Anastasia Romanov. And of course — because EVERY famous person is — she was a Cahill.
There's a tour of the winter palace as well as some graphic descriptions of the murder of the Tsar and his family. Their deaths are compared to the deaths of Dan and Amy's parents, something that up now has been glossed over. I think this book is the turning point where things start to get more "real" for Dan and Amy, and the descriptions of things become more graphic.
For those reviews that complain about things being too easy for Dan and Amy, it is becoming clear that someone (or some organization) is pulling strings for them. As long as they show up, doors will be opened for them. The why and how, though, remains a mystery for later volumes.