Borderland is the first book in the Hex trilogy.
The collegiate are a society which guard new worlds. Charm and Ciren are put in charge of the Techrachate world.
Zoe is used to moving schools (due to the fact her father works in the Army) and fitting in with everyone. This time it's different, and she hasn't made a single friend and it's half term. Then, at a party, she gets her greatest wish, and befriends a girl called Laura Harell. Laura then shows her a Door between worlds, leading to Shattershard, a city in the mountain... When Morgan, the other person from Earth knowing abiut the Door, warns her against Laura, things start to change... Who is Jhezra and why are she and her people preparing for war?
Meanwhile, the Archon of Shattershard, Kal, has trouble dealing with desert nomads - the Hajhim. He knows they will strike... but when?
This is a book with a strong plot and characters. I highly recommend you to read it!