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?

The reader will enjoy:
- the story of Mac and his journey through time;
- learning about American history from the earliest days of colonial times through today;
- learning about a real historic site, the Old Wye Mill, through educational diagrams and illustrations;
- 36 hand-drawn illustrations of Mac, the gristmill, and their story; and
- regional historical education touching on colonial, Civil War, and Revolutionary War times.

The book is intended for readers in second through sixth grade, depending on their reading level.