The Water Road - The Water Road Trilogy, #1

Two women are about to expose a terrible secret that will turn their world upside down. For centuries the great river known as the Water Road separated the Altrerians in the north from the Neldathi in the south. When the Neldathi clans united and struck out across the river, the nations of Altreria formed an alliance, the Triumvirate, to drive them back. For more than a hundred years after, the Triumvirate kept the Neldathi barbarians at bay, fighting amongst themselves across the Water Road.
Antrey is a woman without a country, the daughter of a Neldathi mother and an Altrerian father. She's found a role for herself in Tolenor, the headquarters of the Triumvirate, that's given her access to a secret the alliance has kept for generations. When she finds it, she explodes with rage and embarks on a quest to find justice for the Neldathi people. Strefer is a reporter without a story, desperately working the streets of Tolenor for any kind of lead.
When Antrey flees the city, Strefer slips in and discovers her uncovered secret, stained with blood and fury. It's the story of a lifetime, one powerful forces want to keep her from telling. With the help of a renegade Sentinel, Strefer sets out for a mythical city in hopes she can make the world listen to the truth. Together, they'll inflame the passions of a people and set the world alight. The Water Road - first book of The Water Road trilogy