Castles in the Air — Sheila Myers

In this second novel of a trilogy, William and Ella Durant head towards an increasingly inevitable collision as they wrangle over their father's legacy. When their father, Doc Durant, dies, William and Ella are finally free of his domineering control to pursue their ambitions. William is now head of the family. Without his father's ruthlessness and business savvy, he resorts to creative but dubious financial scheming to save what remains of the family fortune and fulfill his visions of grandeur for the Adirondack wilderness as a playground for the rich. Ella takes off for London to chase her own dream -- to return to high society life, become a successful author, and mingle with literary giants. But she struggles to cope as William tightens the purse strings and restricts her freedom, while her feelings for a gallant and enigmatic French aristocrat turn into obsession.