Ten years have passed since Kate and Cecy married Thomas and James, and England is now being transformed by the first railways. When the Duke of Wellington asks James to look into the sudden disappearance of a German railway engineer, James and Cecy's search reveals a shocking truth: The railway lines are wreaking havoc with ancient underground magic, which could endanger the very unity of England. Meanwhile, Kate has her hands full taking care of all their children, not to mention the mysterious mute girl they rescued from a kidnapper!

Written in letters between Kate and Cecy--and between their husbands--this installment of the cousins' adventures is another satisfying blend of magic, mystery, adventure, humor, and romance.