"It's case five for the Code Busters Club, and the four intrepid young investigators are headed to Washington, D.C., on a school trip. After touring the Spy Museum, Cody, M.E., Luke, and Quinn, along with Mika (a new classmate) and her mother (their chaperone), follow code-based clues from one national landmark to the next in hopes of winning a prize. But who is the furtive figure apparently spying on their group? When one member of their class disappears, it looks as though their trip will end abruptly, but not with the Code Busters on the case. Mystery fans may well solve the mystery before the junior detectives, but that won't lessen their enjoyment of this fast-paced story and its likable characters.

Codes and ciphers crop up throughout the book, with helpful pointers and even-more-helpful solutions appended in separate sections. A must-read for fans of the Code Busters Club series, this will also interest kids who are looking forward to touring the nation's capital."--Booklist.