Molly notices a couple of fish go on by as she tries to say "It's time for Bubble Guppies!". Soon Gil comes by, dressed as a cop and blows the whistle to stop them. Allowing Molly to say, "It's time for Bubble Guppies!"
Goby is on his way to school when he comes to a group of tourists who wish him a happy shrimptennial. He doesn't really know what it is, and the family of lobsters explain what the celebration is, and where it is. At the very top of Big Bubble Tower in Big Bubble City! Soon the bus comes and they say bye to Goby, then wish him a super shrimptennial before they leave. He then resumes swimming to class shortly after.
As Goby mentions this, Oona asks about it and Nonny mentions how he has never gone to Big Bubble City. Mr. Grouper tells them there is a lot of stuff to do in cities. He also explains things that you can find in a City. Like Tall building, Buses, Taxi's, Cars, and so many other things! Then Deema sings: Big Bubble City
After the song, Nonny decides he wishes to open a cake shop and Molly mentions how she wishes to get a cake for the Party. Nonny greets her, then she explains how she wants her cake. Nonny shows her a taxi cake, bus cake, bridge cake, and a pigeon cake. When she mentions what its for, Nonny then tells her she will probably want the Big Bubble Building Cake. After he sees they do not have any already made, he tells Molly he can make one for her.
So, they count the sides for the bottom piece, a big rectangle, then they pick the piece to match it, then they must choose between an oval and a circle. Nonny picks up the circle and adds it to the sheet. They notice that only the triangle remains and Molly asks if he happens to have a triangle. Nonny notes that he doesn't, only a square piece of cake.
It's then Molly decides if they can cut the piece they can make a triangle, so she cuts two corners off and they now have three triangles and pick from one of them to add to the cake. After, Nonny frosts the cake, and a teeny shrimp adds a flag.
Molly is very excited and she talks of the many things a city has. Suddenly, Gil shows up dressed as the Big Bubble Building. She tells him that he better not let a shrimp see him dressed as that, then points out that the shrimp may confuse him for the real building. It's then a group of shrimp come in and hop through the doors of the costume and Gil is then being tickled!
In class they ride Mr. Grouper like a bus. They see the bridge builder, Gil. Along with the PresiTempledent, Deema. And Oona is at the bubble building working as a traffic guard as Clam comments on it. Mr. Grouper then informs the Guppies that they will be going to the city later in the day!
Goby points out that the party isn't until that night, but Mr. Grouper tells them of the many other things they can do while they wait. Such as riding a bus to get there, driving over a bridge. They'll even see many sights, like buildings, people, they may even stop for a pretzel! Then Molly sings: Get Around
The guppies go outside to play with Gil and Oona pretending to be explorers. Goby begins to tell the tale of a lost city. They are in search of the legendary temple of the Golden Pretzel. They notice an odd sign that tells them they are close to reaching the Golden Pretzel temple. Goby also points out it has a caution sign also to watch out out for Pretzelquatl. Oona tells Gil they need to try to avoid it.
Soon they come to the temple and when Gil mentions the pretzel, the thing they are trying to run away from gives chase! He keeps saying "Yummy!" and soon they think they lost him. Gil asks what they can do, since he'll most-likely eat them and they hurry up to get onto the subway. Oona points out that they can ride on 3 different subways and they choose to ride yellow, but first they need to ride the blue subway. Just in time too!
Luckily they ditch Pretzelquatel on the subway and they ride it to the temple of the golden pretzel. Soon Oona and Gil have made it! They go inside and come to the golden pretzel kart in the middle of the room. Both panic when Pretzelquatel seems to already be there! He calls them weird, and explains he only eats pretzels, then asks them if they want some. When they say they do, he lets them and they all live happily ever after!
Gil comments on how he has never seen a pigeon. One comes by and lands on his head and Molly tries to tell him but he doesn't notice. He then asks the audience if they've seen any and when the Little Fish point out there was one on his head, Gil panics a bit and Molly takes a picture. She shows him, but Gil mentions the pigeon isn't in the picture.
The pigeon then floats onto Molly's head, to which Gil smiles as he sees it but she cannot find it. It's then time to get onto the bus!
The Guppies sight-see as they ride into Big Bubble City. All dressed properly and enjoy the many sights, tastes, and sounds! They come to the Big Bubble Building and Mr. Grouper tells them just how high they'll be going. The guppies note how high they are before they get a message telling them that the shrimptennial celebration will be beginning soon!
The Mayor then greats everyone and gives a quick speech. She then tells them she will need a helper and Goby volunteers. So he goes on stage, then introduces himself. She tells him to count down with them and everyone begins to count down from 10. Upon reaching 1, Goby pulls the switch which releases many balloons and confetti and the like!
A small group of shrimp started to dance and sing as Molly gives the Mayor the cake. Fireworks then light up as the song as episode comes to an end...
Molly asks Gil what he thought about it, then tells him that she thinks his shirt is cool. It's then suddenly the shrimp come over and hop inside Gil's shirt again! They then tickle him as he bounces from the stage and Molly giggles.