When Siamwit School faces financial struggles, administrator Paphada decides to merge the Udon Phithak campus with the main campus, Thep Burapha, despite their long-standing rivalry. Saint, the apathetic leader of class M.5/2, once led a gang of bullies in middle school. He’s now forced to deal with the rebellious and hot-headed Shin, with whom he once shared a close friendship, but a violent fallout shattered it. Their rivalry sparks a classroom war, and teachers Jan and Sung must unite to resolve the conflict and facilitate reconciliation between Saint and Shin.