The animals reach London and pull together to work through a mult-million dollar budget and perform the greatest animated circus act sequence you've probably ever seen to Katy Perry's "Firework". (It's a little better than Dumbo)
The American promoter is sold, and signs the contract with "The King of Versailles" (one of the monkeys in disguise) to bring them over to New York.
Meanwhile Captain Chantel DuBois breaks out of jail in Rome, returns to the hospital in Monaco and sings "Non, je ne regrette rien" to revive her men, and break them free of their casts.
While in New York the secret is out, and Gia and the others learn that Alex and pals are zoo animals. They were used as a means to get them back home. Alex, Marty, Gloria and Melman leave to return to the zoo, while the circus animals must struggle to put on a show themselves.
Alex and the others reach the zoo, and realise that it's not how they remembered it. It's very small, with walls to divide them. Suddenly DuBois shows up and the animals are hit with tranquiliser darts. Julien manages to stumble back to the circus to warn the others.
The Zoo Keepers arrive just in time to stop DuBois taking them away, but she takes credit for their capture.
Later, they hold an impromptu event to thank DuBois publicly for bring back Alex the Lion ... and friends, who are all locked behind tall barb-wire fences. DuBois is presented with a cash reward, but she tears up the cheque and loads a poisonous dart. She aims the gun towards Alex ...
When suddenly the circus is back in town, and the others have somehow flown in to the rescue. All the animals perform their circus acts to escape -- Vitaly squeezes through a keyhole to save Marty, while Gia and Alex perform "Trapeze Americano" to get out of his cage. Stefano the Sea Lion falls, and DuBois is almost onto him. Alex jumps to rescue his friend. The little dogs power up their jet-powered skates, and the animals perform the final number - Alex is falling to earth with DuBois, but the little dogs attach themselves to his back to form some sort of jet-pack and he flies to safety. The crowd goes wild.
DuBois is tranquilised, goes a little mad, and knocked senseless back into Alex's cage. Later she is shipped to Madagascar with her men in crates similar to the first movie.
Everyone else is back together to keep the circus on the road, and perform the Circus Afro song one last time.