Water: Rise of the Elementals Volume: 4

Twenty Years have passed since the end of the Elemental War and the Kingdom of Theron is at peace. Elementals and Non-Elementals work harmoniously side-by-side. Maddox and his sister, Catriana, think the greatest challenge they face is unrequited love, but all is not as peaceful as it seems.
Weylyn's father has teamed up with Kieran, a follower of Morfran's. Together, they raised Weylyn's son, Drudwyn, to exact their revenge. Working in secret, they will strike at Stephen and everyone he ever loved. From deep in Theron to the shores of Ionia, the next generation races against a greater threat than anyone ever imagined.