This animation film is the second one in the series about the Smurfs. The Smurfs are little blue fantasy beings that live in a secret place that only a few humans know about. As the movie opens, all the Smurfs in the village are preparing a surprise birthday party for Smurfette (with the voice of Katy Perry), a popular teenage-girl Smurf. They keep all the preparations hidden from her and don't tell her what's happening even though she goes around the village giving big hints that this day is her birthday. She mistakenly believes that the Smurfs don't care enough about her and that all of them have forgotten about her birthday. She starts to feel sorry for herself, especially since she has always felt that she was a bit of an outsider since she was adopted into the Smurf tribe by Papa Smurf (with the voice of the late Jonathan Winters) and does not really know her true birth-origins or where her real family is. This self-pity causes her to run away from the Smurf Village.
The evil Gargamel (with the voice of Hank Azaria) has plans to destroy all the Smurfs by stealing their Smurf-essence so he can make Naughties, which are evil-little creatures the same size as the Smurfs that will do his bidding. Gargamel needs a real Smurf to tell him the secret spell to accomplish this. He sees his chance to capture Smurfette when she runs away. He kidnaps her and takes her to Paris where he uses the Smurf-essence he has and some more he extracts from Smurfette to do fantastic magical tricks in a huge theater in front of sold-out crowds. Two Naughties, a boy and a girl created by Gargamel, pretend to befriend Smurfette. They explain to her, Gargamel was the one that actually created Smurfette and that the Naughties are really her true family. Smurfette, in her naivety, believes them. She feels for the first time, that she has a brother and a sister.
Four Smurfs, Papa, Grouchy (voice of George Lopez), Clumsy (voice of Anton Yelchin), and Vanity (voice of John Oliver) decide to go to Paris to rescue Smurfette. They enlist the help of two human they know Patrick (played by Neil Patrick Harris) and Grace Winslow (played by Jayma Mays). Grace's father Victor (played by Brendan Gleeson) wants to go along, but he is always messing everything up, so Patrick does not want him to go. Victor gets to go anyway. Once all of them arrive in Paris, Victor immediately makes a mess of things.
They confront Gargamel in the theater in front of the audience during a live show to demand he return Smurfette. Gargamel attacks them with magic and turns Victor into a duck. Papa Smurf, Grouchy, Clumsy, and Vanity make a plan to break-in to Gargamel's secret lair and rescue Smurfette before she gives Gargamel the spell that will destroy the Smurfs forever.
Best part of story, including ending:
It's a classic theme of a run-away story, where a young person thinks there is a better life elsewhere and gets tricked by evil ones into temporarily abandoning those that truly love them, until the truth is revealed.
Best scene in story:
The magic that Gargamel demonstrates in the theater when he turns his pet cat from a regular-sized one into a monster-sized one. Great CGI work in this scene.
Opinion about the main character:
She is a bit simple-minded and easily tricked into believing what the Naughties tell her and too quickly gives up on the Smurfs, who are the ones that really care for her.