All is not well with the Smurfs.
Someone wants to build a wall around the Smurfs' Village! When Papa Smurf observes that his Smurfs are fighting with each other, he decides something needs to be done about it, and that’s when the trouble starts. Papa Smurf creates negative versions of the Smurfs. They’re just like the regular Smurfs, except their clothes are a little darker and they don’t have any of the good qualities of the real Smurfs. For example, a black-haired Smurfette has all of Smurfette’s bad habits, and none of what’s good about Smurfette!
When the Smurfs meet the so-called "Grey Smurfs," they want to be friends. But the Grey Smurfs are only interested in going to war against the Smurfs, conquering them, and turning them all into their slaves. Can Papa Smurf fix this mess he created?
