The film begins exactly where the last film left off, with the muppets finishing the filming of their movie. A lively song and dance breaks out where they decide what this movie should be about. They settle on making a movie about a Muppet world tour after Ricky Gervais whispers the idea in Kermits ear. Ricky Gervais than introduces himself as Dominic Badguy, a tour agent who has produced tours by Rhianna and U2. He wants the muppets to take their show on the road while Kermit thinks they should stay put and hone their act. But with some convincing from the other muppets, especially Walter, Kermit agrees. Dominic gets on the phone with Constantine, a frog that looks exactly like Kermit except for a mole. Constantine is the most dangerous criminal in the world and he has just escaped jail in Siberia.
He tells Dominic to meet him in Berlin and Dominic tells the muppets their first show will be in Berlin. Kermit leads them to a tiny broken down theater and says it is all they can afford. However, Dominic convinces the muppets to ignore Kermits practicality and go for the biggest theater in Berlin which happens to be next to an art museum. Kermit is upset none of his friends listen to him and Dominic suggests a walk along an abandoned canal. There Kermit is accosted by Constantine who glues a mole to Kermits lip.
The villagers think Kermit is Constantine and arrest him and send him to Siberia. Constantine paints his lip green and infiltrates the muppets show. He faints from stage fright but the show is a sold out success anyways. While the show goes on, Constantine and Dominic break through the wall of the theater into an art museum and steal precious paintings.
The next day Detectives Eagle and Jean (Ty Burrell) examine the museum. 2 of the paintings stolen were valuable but one was not. They notice a coin Dominic left behind that says The Lemur. Dominic is the 2nd most wanted criminal behind Constantine. Dominic and Constantine find instructions behind the worthless painting that will lead them to the crown jewels. They must get a key from Madrid so the next stop on the Muppets tour is Madrid.
Kermit is taken to Siberia where prison guard Nadia (Tina Fey) sings a song about the most glorious hotel in Russiathe big house. Kermit is thrown into jail with all the other hardened criminals, but holds out faith his friends will save him. The muppets perform in Madrid and Kermit (Really Constantine) lets them do whatever they want which is highly unlike Kermit. He also sings a song about his love for Miss Piggy. During the show Constantine and Dominic break into a Spanish museum where they break dozens of priceless busts until they find a key inside one of them. The key says they must get a locket from the Irish National Bank in Dublin so the next stop on the Muppets tour is Dublin.
sKermit is disheartened that none of his friends have rescued him. He tries to escape but Nadia always catches him. She convinces him to direct the prisons annual revue (convincing being more of a threatening term here). When they arrive in Dublin, Walter begins to suspect something is wrong with Kermit. He sees Dominic sneaking around and follows him.
He discovers Dominic has been paying for good reviews and good turn outs in order to distract the muppets and the public from his crimes. Jean and Eagle examine the museum in Spain and realize the muppet shows have happened in conjunction with each crime. They interrogate the muppets but can discover nothing. Walter and Fozzy realize Kermit is really Constantine. They escape with Animal, who has realized something was fishy all along. They run to Russia to rescue the real Kermit. Kermit is directing the prisons revue and Nadia is falling for him quickly. Kermit finds he can direct these inmates better than his own family.
The show in Dublin begins and Constantine and Dominic steal the locket from the bank. During the show Constantine proposes to Miss Piggy and insists that their wedding be in 2 days in the tower of London-where the crown jewels are kept. Walter, Fozzy, and Animal find Kermit and apologize for not seeing through Constantine sooner. They use the revue as cover for a massive jailbreak.
They head to London to save Miss Piggy. Miss Piggy, the muppets, and Celine Dion sing a song about how the whole thing doesnt feel quite right. Kermit sneaks into the wedding and Miss Piggy realizes there are 2 Kermits. Constantine urges her to marry him and Kermit hangs back. This makes Miss Piggy realize who the real Kermit is. Dominic hires a team of criminal babies (Muppet babies) to break into the crown jewels room. He uses the locket and the key to unlock the safe.
He has the crown jewels. Constantine grabs Miss Piggy as hostage and drags her to the helicopter. Dominic is there in a lemur costume and he tells Constantine he is double crossing him. Constantine says the point of a double cross is that it is secret and throws Dominic out. Constantine tries to take Miss Piggy away but Kermit and the other Muppets defeat him in an action sequence (the movie comedically calls out its own plot devices) and are saved and together. The Muppets apologize to Kermit for not listening to him. Nadia comes and says Kermit must go back to jail for leading the jailbreak.
The muppets offer to go to jail in his place. Nadia is touched and says Kermit can be free as long as they do a final performance in Siberia. They finish with a happy song about being together again..