Between Starfalls - Children of the Nexus, #1

Never leave the path. It's sacred law, punishable by exile.  When her son goes missing in the perilous mountains, Kaemada defies the law to search for him. She enlists the help of her hero brother, a priestess berserker, and a fire-wielding friend. But the law exists for a reason. When the search party is captured by the mythical Kamalti, they learn that Kaemada's son was sent to an ancient prison city.
As they battle for freedom, they discover a horrible truth that will change the future of both races forever. With their world in upheaval, Kaemada must find a way to peace if she's to save her son-but tensions between the two races are leading to war.