"The Sorcery of Maltrochu" is a Johan and Peewit episode that appeared in Season 2 of the Smurfs cartoon show.
The episode opens with Biquette playing smurfball with the Smurfs and having a great time. Soon Peewit and Papa Smurf arrive with some chemicals when Clumsy runs into him and they greet each other. He soon explains how he seems to have mastered alchemy, but he creates an explosion. Papa Smurf tells him to be on his way.
Later at the castle his alchemy interrupts the King's dinner. Johan decides to silence Peewit by bringing him a whole chicken, hoping the King can also eat in peace. However, he eats quickly. He continues his experiments when he finishes and decides to tell Johan. He accidentally squashes him in a door. He tells him he wants the King to see. He asks for his crown but snatches it when the king clutches it. Peewit rubs his crown with the pebble, and the crown turns to lead. He says it hasn’t been done, but Johan says it was supposed to be the other way around.
Peewit is now being forced to do chores for the King. When he uses a pitchfork he sees a dog talk to him. He gets shocked by it and runs for the king. The king tells Johan he doesn’t actually want him to work two years, he only wants to eat peacefully. Peewit calls for Johan to arrive and tells him about the talking dog. They arrive at the barn, but see the dog fleeing. They give chase and catch him. Peewit tries to get the dog to talk, but it barks. Because of this, no one believes him. Johan decides to feed the dog. Later they hear the dog talk in his sleep causing Johan to realize peewit was telling him the truth. The dog admits he’s actually a Knight named Thierry. He explains how he was changed and why he didn’t speak. They try to change him back to stop the baron’s plan. They decided to hide him at an inn.
Meanwhile, the baron is training when his announcer tells him of arrivals and he reluctantly agrees to let them in. They tell him Peewit is gonna marry the princess. The heroic duo then see the potion and decides to wait. The innkeeper is revealed to be traitorous and is shocked that the dog can speak. They spring the trap but Peewit spills a bit of potion on himself and turns to a dog. They return to the inn to find Thierry but the baron has captured him. They ride and find the smurfs. Soon they tell him the story and try to make an antidote. The baron rides to the castle of the princess and tries to propose again. It’s shown she still loves Thierry.
He tells her what happened and she is forced to marry the baron. The Smurfs make an antidote and succeed. They then ride to the castle but find her just about to marry the baron. Papa Smurf summons Feathers and they ride off. The baron prepares for the wedding and the Smurfs spy on them. The Smurfs and their human friends make a plan. They scare off a guard and prepare to invade. The guards try to attack but are defeated and some are turned to dogs. They run to the dungeon and return the dog to his human form. They then crash the wedding and defeat the baron by turning some stolen gold to lead. They tell the king he lost a fortune but gained a son.