The Ancient Gate - The War For Ezryn, #1

After years of adventure and many close calls, Desa Kincaid wants nothing more than a quiet life with her family. Her partner, Kalia, has been elected to the city council, and their adopted son, Brendan, is growing up strong and healthy. But when a new threat comes to her world from beyond the stars, Desa must embark on a journey that will take her across dimensions. Anna Lenai never wanted to be famous; she never asked to be in the spotlight.
That kind of thing just happens when you save the world enough times. After fending off an alien invasion, Anna is ready to settle into a comfortable routine. But the arrival of a stranger from another dimension pulls her into a new adventure, too. Together, the two must face an enemy that threatens to destroy both of their worlds.