An Animated Adaptation of The Smurfs comic book story of the same name (original French name Le Centiéme Schtroumpf).
As the story begins, Papa Smurf sees that the village has been beset with a streak of bad luck. He discovers from his books that in the 654th year of Smurf, an unusual eclipse of the June moon will bring ill winds, great misfortune, and a hundred years of bad luck that can only be warded off by performing the Dance of 100 Smurfs. Papa Smurf then goes out to count how many Smurfs there are in the village to see if there is enough of them to perform the dance, and finds out that he is only one Smurf short of a hundred.
As he tries to figure out how he can complete the dance with only 99 Smurfs on hand, Vanity is busy trying to assemble a new mirror from a sheet of silver, causing so much noise with his hammering and polishing that the Smurfs get upset with him. Taking his mirror out into the forest, Vanity gets it finished just before it starts to rain. As he is about to bring his completed mirror back to the village, a lightning bolt strikes it, and soon Vanity finds himself face-to-face with his reflection come to life. Even weirder is that Vanity's mirror reflection does the exact opposite of what Vanity does and speaks his sentences in reverse.
Despite this, Papa Smurf sees that he now has a hundred Smurfs to perform the Dance of 100 Smurfs with, and so he begins practicing the dance with the hundred Smurfs. Unfortunately, Vanity's duplicate does the exact opposite moves of his partner and ends up making a mess of things. Even Vanity finds it hard to live in the same house with his duplicate, so he has the duplicate thrown out of his house by his accidentally tumbling down the stairs and out the door. Frustrated, Vanity's duplicate goes back to the mirror and tries to reenter it when lightning strikes it again, and this time Vanity's duplicate is now a normal Smurf who can speak and act independently of Vanity. With Vanity and his duplicate now separate Smurfs from each other, Papa Smurf successfully performs the Dance of 100 Smurfs.
This episode has the following examples of
- Getting the Boot: Jokey near the end when he tries to impersonate Papa Smurf as his Mirror Self.
- Mirror Self: Not only Vanity, but also Jokey posing as Papa Smurf's mirror self as a Practical Joke near the end. Papa Smurf wasn't amused when he found out.
- Synchronization: Vanity and the hundredth Smurf were linked together mirroring each other's movements until the hundredth Smurf fell down a set of stairs in Vanity's house and was shown the door.
- Verbal Tic: The hundredth Smurf speaks the same sentences that Vanity speaks, only with the words arranged backwards.
- What Happened to the Mouse?: After Vanity's mirror self becomes a real Smurf, he is hardly ever seen again.
