Dr. Zomboss invents a Cold Crystal, which is capable of freezing Neighborville, thus creating an eternal winter. Both plants and humans would be buried in snow and ice. Most of the benevolent, zombie-battling plants are chilled and immobile, and now, Zomboss hopes to lead his cold-blooded zombie troops on a mission to overrun the city. It’s up to Nate, Patrice, Crazy Dave, and the fieriest plants to adapt, fight on, and save Neighborville—with the help of pirates.