An early chapter book that features the true story of the Old Wye Mill in Maryland, as told by a mouse who travels through time to different periods of US history. Mac is a mouse who lives at the oldest operating gristmill in the United States. When he falls through the hole in the center of a millstone, he accidentally travels back in time, setting off a journey that follows the very history of the mill itself. Mac visits various times in the history of the mill, from its beginnings in 1682 through its part in both the American Revolution and the Civil War. While he tries to get back to his own time, he faces dangers and meets long-lost relatives who help him on his journey. Will Mac find his way back home?