Thunder in the highlands; horses’ hooves clanging on the cobblestones; strange men moving warily through the night carrying strange cargo; the tramp, tramp of weary feet as General Washington's troops make their way to West Point—and underneath a current of restlessness, a foreboding of evil, a nervous tension that none can explain. It is the year 1780. Benedict Arnold has been appointed commandant at West Point and his family comes to live at the Robinson House, center of military activity in the Hudson River valley country.

This is the story of Jed Drake, a courier for General Washington; his sister Emmiline, who works as serving maid in the Arnold household, and their young brother Kirby, who wishes he were older so that he too could fight in the war. Through no desire of their own, the Drakes become involved in a series of swift-moving, mysterious events that lead to the exposure of Benedict Arnold and his attempted betrayal of West Point, and the capture of Major john André, British spy.

This exciting story blends mystery, military intrigue and suspense against an accurate, colorful background of American history. Most of the action takes place in the Hudson River valley country and at the Robinson House, Arnold's official residence at West Point. Molly Pitcher, George Washington, Alexander Hamilton, Lafayette and many other famous characters from history are woven into this story of Arnold’s treachery.