Lily and Farmer have to save the village from a slobbering monster. Gargamel transforms Rowena into a Smurfette in an attempt to capture Smurfs, but Mummy begins adoring her because she reminded her of her doll from her childhood.
Smurfette and Grouchy argue over who takes better care of Baby - a competition then begins between the two babysitters; Blossom dreams of going to Mars and can count on her friends to help.
Handy creates a machine to translate animal sounds, but Clumsy accidentally breaks it. Following a blunder by Dimwitty and Clumsy, they find themselves wandering in parallel universes, trying to return to their own.
To prove to Storm that they can also have great adventures, Bubble and Firefly decide to steal one of Rowena's teeth, which is about to fall out. Gargamel causes a long dark night to fall on the forest in order to capture the Smurfs.
To respect a Smurfy tradition, Chef and Blossom must find a thirteenth dessert for the Christmas meal, which will take them straight to Gargamel. Jokey wants to prove to everyone that he's capable of looking after Baby Smurf.
Arguing about who should drive the truck, Clumsy and Dimwitty accidentally misplace it in the forest. Without realizing that it's one of Gargamel's traps, Lily discovers a sudden passion for some rocks she's found in the forest.
To make Azrael docile, Chef prepares an irresistible pie that Gargamel will serve. Unfortunately, Mummy eats it and demands that Gargamel make it again; Dwayne is a huge fan of Lily's waffles but she refuses to make any more for him.
Meteorite finds Gargamel's cursed disco mushroom in the forest that she brings back to the village to dance with the Smurfs, not knowing it is a trap. Diaper Daddy decides to go looking for a place where he feels he is better regarded.
In order to prove to his uncle that he can be a good Smurf hunter, Dwayne makes a potion that gives him the qualities of a hunting dog, but also his faults. Meteorite's drum, cursed by Gargamel, bewitches the girls and leads them to Gargamel.
When the moon loses its glow, the Smurfs decide to fly there to relight it, without knowing that it is Leaf who unintentionally caused the catastrophe.
While trying to help Farmer grow his plants faster, Papa Smurf accidentally gives the potion to Baby, who starts growing nonstop. Gargamel gives Azrael supersonic hearing so that he can help Gargamel to locate the Smurf village.
Farmer uses Willow's carnivorous plant to keep the insects away from his crop, but he soon loses control of it. Papa Smurf turns into a giant arachnid after a spider accidentally intrudes into the potion which was supposed to boost his athletic abilities.
