Green City Wars - Adrian Tchaikovsky

The plot kicks off when a peaceful existence is shattered by an invasion from a rival city that employs various forms of biotechnology. Orso is caught in the middle of a brutal conflict and must use his skills to protect his home while uncovering the truth about why the war started. Along the way, he discovers that the leaders of the Green Cities are hiding dark secrets about the origins of their living homes. The story moves quickly through intense battles and clever twists as Orso tries to stop the cycle of violence before both cities are destroyed. It is a gripping tale about the cost of war and the dangers of playing god with nature.