In February 1887, Caitriona Wallace and Émile Nouguier meet in a hot air balloon, floating high above Paris, France -- a moment of pure possibility. But back on firm ground, their vastly different social strata become clear. Cait is a widow who because of her precarious financial situation is forced to chaperone two wealthy Scottish charges. Émile is expected to take on the bourgeois stability of his family's business and choose a suitable wife. As the Eiffel Tower rises, a marvel of steel and air and light, the subject of extreme controversy and a symbol of the future, Cait and Émile must decide what their love is worth.