Kase Garrick is more powerful than ever in this new adventure of the How to Set the World on Fire series, but will his powerful be enough? Kase and his friends are on the run. The Triple Crown has failed to capture them, but Cali, Lenia, Talen, and Kase feel like prisoners nonetheless. The fugitives have taken safe haven in an ancient land, where they've made an abandoned castle their home. They return to the realm to gather supplies, but they risk capture every time they step out of the shadows. Luckily for them, a new enemy has taken the spotlight as the Triple Crown's most wanted criminal: The Unicorn Knight. Wielding a flaming sword, the Unicorn Knight hunts down allies of the Triple Crown, eliminates High Guardians, and strikes fear throughout the realm. On the surface, it appears that the Unicorn Knight is doing Kase a favour by targeting his enemies, but when Kase is forced to confront the vigilante, he must decide whether the Unicorn Knight is friend or foe.