The episode begins as Molly tries to say "It's time for Bubble Guppies" but Gil is working with a jackhammer and is being too loud! She keeps being interrupted until he accidentally gets drilled underground! She asks if he's okay and he suddenly pops up to declare that "it's time for Bubble Guppies!"
The episode begins as Goby is on his way to school, only to stop when he hears noises that sound like construction work. He goes to see a crab hammering wood, who then yells for the other workers to stop and asks another crab, named Pronto, to grab a hard hat for Goby to keep him safe. The crab explains that they're building a house and he shows Goby things they use for it, such as the blueprints, materials, and tools. He has to get back to work through but tells Goby he can keep the hard hat before he leaves and resumes going to school.
At school, Goby is asked about the hat, which he explains to them and Oona asks what the word "Construction" means. Goby then explains that he was watching a group of construction workers build a home! Soon the entire class gets an idea to make a house for Bubble Puppy. But before they can do any of this, they need to learn about all the tools one may need when it comes to building things.
Deema is running a hardware store and she asks Gil what sort of tool he needs. Gil doesn't know what it is, but its used to hit nails and makes a "bam bam bam" sound. Deema thinks she has it, and brings out a saw but Gil tells her that doesn't make the same sound as the tool he needs. Deema tries again, this time bringing out a wrench but they decide it's not what Gil needs either. After searching, Deema can't find the right tool and asks for help.
The little fish point out the Hammer and she gives it to Gil, who deduces it's the tool he needs! He thanks her before leaving. Then Goby sings "Construct With Me!" Then it's A Hammer And Cheese Sandwich Lunchtime.
Gil is struggling, trying to open his toolbox when Molly comes over to ask him what's wrong. He explains the problem and she offers to open it for him with her "Magical undersea powers". Molly makes Gil close his eyes while he asks, she then uses the key she had to open it and giggles as Gil then decides he wants to try.
Unfortunately, it didn't do a single thing and he swims away as she continues to giggle.
In class everyone is going over the blueprint they made for Bubble Puppies house. Deema suddenly asks what they would build the house out of and Molly asks Mr. Grouper. He explains they'll need really strong materials and asks the viewer what sort of materials they'll need. Such as Wood, bricks, and glass. Then Molly sings "Build Me a Building".
The guppies go outside to play. Deema decides she is a Princess as Goby tells a story about her and the royal construction crew. One day the princess was sitting on a hill with her favorite snack, until she flees in surprise as a Dragon eats all the graham crackers and flies away. Deema decides she'll need to keep her graham crackers safe by putting them away. The construction team decide they'll build her a fortress! But she wants it made out of paper...?
They build the fortress, which Deema likes, then she offers a snack but the Dragon shows up again! Quickly they lock the Graham crackers inside and hide but the dragon simply burns down the fortress and flies away after eating the crackers! Deema then decides she wants her fortress made out of ice. The dragon ends up melting this fortress also, eats the crackers and fly away. The Princess then decide this time they need to pick the right type of material. She offers cheese, cardboard, then finally settles on Bricks after Molly brings it up. And so they build a fortress made out of bricks and place the Graham Crackers inside.
This time the Dragon can't burn down the fortress. Eventually it makes him cry and they explain they built the fortress out of bricks so he can't burn it down. He really wants more graham crackers and Gil suggests that he just asks for more and Deema happily hands one over to everyone as they all live happily ever after!
Molly is explaining materials when Gil interrupts and presents a house that he built. A house out of Graham Crackers? Bubble Puppy begins to eat the house and Molly tells him it probably wasn't the right material. Oona then comes over to tell them its time to begin building and everyone swims to the construction sight!
The guppies hide the Blue Print from Bubble Puppy, who wants to see but they keep telling him its a surprise.
Mr. Grouper mentions they may need help though when the Crabs from earlier suddenly arrive! They offer to help and Goby shows them what they plan to build.
In no time they manage to build it. Bubble Puppy is very happy and loves his new dog house and goes to play on it. Bubble Puppy licks Goby and the viewer as the episode ends.
Molly is very happy that Bubble puppy likes his new dog house which would get destroyed in The New Doghouse!. Gil then comes over and asks her to open his toolbox again with her magical undersea powers. But she promises to do better then that and unlocks it with the key!