The main characters must travel throughout the past and future to get items to achieve their goal while being chased by the antagonist, who controls hordes of zombies.
Pretty funny tbh because some of the worlds in PVZ2 feel similar to bo1 maps (lost city being Shangri-La, frostbite cave being COTD, etc)
Fiction is so vast and limitless that if you look hard enough, there are always two stories that feel similar, which is amazing.