When young Harry Sandwith, a Westminster boy, becomes a resident at the chateau of a French marquis, he begins a series of adventures with the family. One day, an ill-advised trip takes them to Paris at the height of the French Revolution. Suddenly Harry and his party are beset with perils at every turn. As they struggle to escape, imprisonment and death reduce their number. Finally, Harry finds himself in charge of the three young daughters of the house. Only he can save them from the reign of terror—and certain death.