The Tamerlane trap

the long version

"The Biblio twins haven't had a very good year. And to top it all off, this Christmas finds them trapped in the dark of an underground library. When they finally emerge, they will be sent on a chase for clues that will eventually lead Tom and Becky to the Library of Congress. Once there, they will have to use everything they've learned to decode the secrets of the Main Reading Room and reach their final confrontation with the mastermind of all their puzzle-solving adventures ..."--Cover back.