River of painted birds

"Married at fifteen, "in loneliness and lust" as she herself puts it, Isabel Keating accidentally kills her abusive husband six years later and is forced to flee 18th century Ireland disguised as a man. She boards the Bonaventure, a ship bound for America, only to discover, once she is on the high seas, that thanks to her ignorance of geography and the captain's greed, she is not on her way north to Boston, as she had intended, but south to the Spanish colonies. From the ship's owner, Garzón Moreau, who is also on board, she learns of the perils and rewards of continuing south to the small coastal city of Montevideo and uses her small stock of money to invest in Garzón's export ventures. Like Isabel, he too is something of an outcast, albeit a wealthy one thanks to his ability to evade the Spanish Crown's import and export regulations, and to his skills as a smuggler. They both have strong reasons to resist a relationship that goes any deeper. Garzón is half Indian and well aware that the Catholic Church forbids mixed marriages. And Isabel is a fugitive with a troubling secret. They join forces with an unconventional priest whose determination to save the native people from slavery impels him to leave the safety of his mission near Montevideo to establish a new one inland, on territory controlled by Garzón. Their partnership provides them with freedom from close scrutiny from the Crown and the Church, while forcing them and the Indians who join them on their new venture to make choices that will affect not only their own lives, but the future of the Spanish colony itself."--Amazon.