Derek and Michael are travelling with their grandmother to Washington D.C. and on the way stop at Harper's Ferry Civil War Museum to visit. Curiously enough, after trying on Union soldier uniforms, the boys pass through a door and find themselves in 1862 in Antietam just days after the battle. They think that it is all a game, a reenactment, until they meet Abraham Lincoln and witness the horrors of war. When their pocket watch chimes, they have one hour to return to the museum or they will be trapped forever in 1862 . . . will they make it in time?