What is the main plot in the novel, Warcross?

The novel, Warcross, has one major plot line - Emika's quest to find the mysterious hacker Zero and stop him. Secondary to that is Emika's team's, Team Phoenix Riders, mission to win the Warcross Championship, as well as Hideo's quest to control the minds of NeuroLink users to stop them from making bad decisions and Zero's attempts to stop him.