River Aria is narrated by Estela Hopper, who, as a ten-year-old girl living in the impoverished fishing village of Manaus, Brazil in the early 20th century, is offered a twist-of-fate opportunity to study opera with an esteemed voice instructor. During her years of instruction, Estela, who is talented, passionate and dramatic by nature, dreams of leaving Brazil to perform in New York. But as there is no way for her beloved instructor to convince the managers of the great Metropolitan Opera that they should bring on a mixed-race immigrant who grew up on the banks of the Amazon River to become an elite performer, she accepts what they do offer, a position in the sewing room...and leaves Brazil on a ship with her cousin JoJo in the year 1928.

The challenges that befall Estela and JoJo in New York are plentiful. Estela's father, an Irish American who came to her village twenty years earlier (at which time she was conceived), has a plan for what her life should look like once she is settled. Her relationship with JoJo changes drastically when he learns he was lied to about his own parentage, and again when he takes a dangerous job working for the owner of a speakeasy. And of course her personal challenges of finding some modicum of success in a place like New York are not only enormous but crushing to her once robust sense of self.