Seeking a Quantum Tree - Ancestors of Jaiya, #4

Journey to the country of Jaiya, in a world not quite like ours. Here the humans wield magical powers and fight against an Empire which seeks to enslave them, but they share their world with insect people and trollfolk, and stranger things lurk in the shadows.Sena is a Jaiyan secret agent, sent to warn a neighboring country about an upcoming attack on them by an insane general. When the invasion happens sooner than she expected, she must work with the handsome Taavid, a wealthy businessman and Jaiyan exile, to help save the other Jaiyans trapped in the occupied zone.
But General Drozniya controls the occupied zone, and he is obsessed with the Quantum Tree, a legendary source of mystical power which could destroy the world!Note: Quantum Tree is meant as a standalone with a "happily ever after" ending. However, the hero in this book is the son of the hero and heroine of Book 3, and he and the heroine are parents of some of the characters in the original Jaiya series.
The romance is on the sweet side, but there are some disturbing supernatural events, along with some violence, not very explicit, and some references to the horrors of war, more implied than shown.