In this history-filled, time-traveling fantasy, a visit to a museum unlocks a door to the past! When their grandmother drops them off at a Civil War museum, Michael and Derek don't expect to have a life-changing adventure, but that's exactly what happens when the mysterious museum keeper invites the boys to play a "game." Michael and Derek put on Union soldier uniforms, step through a secret door, and suddenly find themselves transported to Antietam just after the battle. At first the boys think they are taking part in a re-enactment, but before long they are convinced everything they see is real. They witness first-hand the human cost of the devastating battle and meet a very convincing Abraham Lincoln. Readers will also be left wondering whether the trip was just a game or a real experience, especially when the boys find a surprise that just might validate their trip back in time.