"When middle school puzzle-master Sam and history-whiz Martina win a contest for a summer trip across the United States, they soon discover that they've been drafted into something vastly more exciting. Joining Theo, the last descendent of an American icon, they begin an extraordinary adventure across national landmarks and natural wonders, following clues to find seven artifacts left behind by the Founding Fathers. Together, these historical artifacts are keys to unlocking Benjamin Franklin's greatest invention--a powerful secret weapon. Each of the artifacts is hidden and protected with puzzles, riddles, and traps. This has kept the invention safe until now. Gideon Arnold, dangerous descendent of the infamous Benedict Arnold, is on the chase!"--Back cover.