When Greg Heffley's middle school closes due to snow, his neighborhood transforms into a winter battlefield. Rival groups of kids claim territories, build massive snow forts, and engage in epic snowball fights. And in the crosshairs are Greg and his old friend, Rowley Jefferson.

It's a struggle for survival as Greg and Rowley navigate alliances, betrayals, and warring gangs in a neighborhood gone wild. When the snow melts, will Greg and Rowley emerge as heroes? Or will they not even know if they'll make it out alive?