The Black Circle (The 39 Clues, Book 5) by Patrick Carman
The highly anticipated Book Five of the #1 bestselling The 39 Clues series.
A strange telegram lures fourteen-year-old Amy Cahill and her younger brother, Dan, deep into Russia and away from the only trustworthy adult they know. Signed with the initials NRR, the telegram launches a race to uncover a treasure stolen by the Nazis and the truth about the murder of the last Russian royal family. All too soon, the treasure hunt starts to smell like a Lucian trap. But the bait might just be irresistible . . . what will Amy and Dan risk to find out what really happened on the night their parents died?