Massachusetts, 1777...Both the United States and the Mason family are fighting for survival.

Adult twins Jill Mason Goodwin and Joanna Mason McGregor grew up hearing stories of the heroic Zachariah Mason, their patriotic ancestor who fought in the American Revolution. As a birthday surprise for their dad, the twins use their new positions as time-portal guardians to arrange a family trip to 1777. But the excursion derails when their parents refuse to time travel.

Jill, Joanna, and their husbands travel to 1777 and discover someone else is controlling the portals. Jill and Rob must solve a case of mistaken identity while defending themselves against British soldiers, wild animals, and desperate women. In Boston, Joanna and Liam must solve a murder and defend an innocent man from being hanged without becoming victims themselves. In their adventures, Jill and Joanna discover secrets that threaten to tear the Mason family apart in both the eighteenth and twenty-first centuries.