Another year has passed and Christine, Sadie and Henry have graduated and are preparing for college. When a mysterious man attacks a friend, Isaac Morrison gives chase without thinking. He follows the gunman into a tunnel and finds himself back in history. Another adventure awaits.

In 1833, Isaac begins work as a millwright and farm hand at Mill Creek. His new friends have a mystery of their own, as there seems to be a saboteur at work, but Isaac is not sure who he can trust. Will he be able to figure out what is going on at the mill? What can he do when-and if-he finds the mysterious perpetrator? With no key of his own, how will he ever get home?

The mystery of the key becomes more complex and the plot started by Callum Lewis years ago thickens as Isaac races to stop a family bent on revenge.