A New York Times Bestseller written by Blue Balliett.

Supersleuths Petra and Calder, along with Calder's friend Tommy, have been drawn into another mystery -- this time involving a Frank Lloyd Wright architectural masterpiece, the Robie House.  When the kids' sixth grade class attempts to save the house from demolition, eerie events are reported: Voices float out from within, shadows shift behind the art-glass windows, even the roof moves.  Soon the three are involved in a frightening search for ghosts, hidden treasure, and a coded message left behind by Wright.  Can thy pursue justice and escape with their lives?