War Master’s Gate by Adrian Tchaikovsky is book nine in the Shadows of the Apt series (Tor £12.99), now available.
“Relentlessly advancing towards Collegium, the Empire is again seeking to break down its walls. The mighty imperial armies have learnt from their failures, and Empress Seda will brook no weakness in her soldiers. However, Stenwold Maker has earned his title, and the War Master has strategies to save his city. His aviators rule the skies – but the Wasp Kinden Empire has developed a terrifying new aerial weapon.
Yet the campaign may be decided far from marching armies and the noise of battle. In an ancient forest, where Mantis clans pursue their own civil war, the Empress Seda is seeking lost magic. Some dangerous shadow of old night is locked up among these trees and she is wants its power. Cheerwell Maker must stop her, at any cost, but will their rivalry awaken something far deadlier? Something that could make even their clash of nations pale into insignificance...”