The Black Circle

The Black Circle is the fifth book in the 39 Clues series by Patrick Carman. It follows the adventures of Amy and Dan Cahill, two teenagers who are searching for 39 clues that will lead them to a powerful treasure.
In this book, Amy and Dan are lured to Russia by a mysterious telegram. They soon find themselves caught up in a dangerous game of cat and mouse with the Lucian, a secret society that is also after the clues.
Amy and Dan must travel to St. Petersburg, Moscow, and the Ural Mountains in order to find the next clue. Along the way, they must face off against the Lucian, corrupt Russian officials, and even a ghost.
The Black Circle is a fast-paced and exciting adventure story that is sure to keep readers on the edge of their seats. It is a must-read for any fan of the 39 Clues series.