The fourth book in Jenn Burke’s “Chaos Station” series is titled “Inversion Point.” The friendship between Zander and Felix has endured the Human-Stin War, imprisonment, and even Zander’s real death and resurrection. Zander now has a new task as the Guardians’ envoy a race that was just found to pose a threat to intergalactic harmony. They have to navigate their doubts and hold onto their love while stopping another galactic war with Felix at their side.