Molly and Gil find a pirate looking for buried treasure on their way to school and ask why he can't find it. The pirate gives them a map to the treasure and tells them if they can figure it out, he'll make Molly, Gil, and their friends honorary pirates. So the Guppies learn all about pirates, such as how to act like a proper pirate, how to dress like a pirate, and other fun pirate stuff, and they eventually go on a journey to find the treasure!
Molly introduces herself and tries to say "It's time for Bubble Guppies!". She hears someone say "Arr..." and other pirate things and sees Gil digging a hole in the sand. She asks the audience what they think Gil is pretending to be and she tries to tell him its time for bubble guppies when he suddenly pops out of the ground and says it first!
Molly and Gil are on their way to school when they hear a strange sound! They hear someone talk and the Little Fish point out a parrot on the ledge above them. Molly and Gil follow it across a very dug up/holey area and come to a frustrated lobster who is momentarily blinded by its bird. He demands to know who is there and Molly and Gil introduce themselves. Gil asks the pirate if he's digging for treasure, then tells Polly that he cannot find the X she keeps telling him to search for. Molly asks if he has a map he could use, but he admits he doesn't know how to read it.
Gil and Molly both wish to take up an interest in pirating. The pirate lobster tells them that they can be part of his crew if they can find the treasure. To sweeten the deal he also promises to share the treasure with them and he takes his leave. Molly and Gil then go to school to tell everyone what happened to them and everyone begins to overlook the map. Deema asks about the map, which Mr. Grouper explains the images are landmarks, which helps a pirate know where they are at. The guppies also discuss the X and soon everyone wants to become a pirate! They discuss pirate hats, ships, and buried treasure. Then Gil sings:X Marks the Spot! (Song)
Deema decides to open her pirate store when Gil comes in to ask for a pirates costume. She then asks him to spin the ships wheel to determine what pirate costume piece he'll recieve! Gil spins it and it lands on a pirates hat. So they use the map of the store to figure out how far they need to go from the wheel to reach the pirate hat. They find it very close nearby and Gil puts one on. Deema comments on it, then Gil spins the wheel again to recieve another pirates item. This time it lands on an eyepatch! Which happens to be much further away.
Molly laughs at the joke when she comments on how much she likes Gil's eyepatch. He asks if she wants to know of something more piratey and he puts on a second eyepatch. This proves problematic as he keeps bumping into many items...
In class, Goby sees Nonny painting a pirates flag as he uses his spy-glass. Molly and Oona have a picnic while Mr. grouper turns himself white in order to be a white whale! They see Gil just sitting there however and they overlook the map again and soon its time to go outside!
Two pirates, Oona and Molly decide they want to go on a picnic so they prepare their minivan and head out onto the road! Oona asks Molly where they will go, to the very top of picnic peak and Molly overlooks her map. They should first pass by Cactus Hill and Oona points it out up ahead. They pull over momentarily to take a picture and a giant white whale shows up! So the girls quickly flee and continue to drive. Oona asks how far away Picnic peak is and Molly mentions that the next landmark should be Stoney Arch. Once again they pull over to take another picture, and again the whale shows up!
Oona asks if the whale was following them but they do not see him. They quickly drive the whole way to the top of the peak and overlook the view. Molly points out their ship and the whale shows up, again! The two pirates quickly flee and Molly mentions they accidentally left their map behind!
Molly then mentions if they remember the landmarks they visited earlier then they can just drive pass tchem again in order to reach their ship. So they pass by the first spot, then come to three hills: Stone, Cactus, and Sandy. They remember it was Cactus Hill and upon arriving to their ship they see the giant white whale again. Oona finally asks why the whale keeps chasing them and he admits to have never seen a pirate before and he asks the girls if they would take a picture with him. Then Molly invites the whale to their picnic and on top of Pirate Peak they all pose for a picture and live happily ever after... Deema then sings Digging Dance!
Molly explains the fundamentals of being a pirate. Such as learning how to dig, or having your own personal Jolly Rodger. Gil warns Molly to step aside so that she doesn't get tangled up when Bubble Puppy grabs the rope and gets him tangled instead!
The guppies go to look for the treasure! Their first stop is spyglass peak, then to Bucaneer bridge which they then cross. Gil then warns everyone to be careful since its a long way down! They then finally come to the beach and they come across the final landmark, Parrot rock. Gil mentions how close they are, then he asks the viewers to help them look for the X. Seconds later the X is found! Gil asks the viewers to help digging the treasure out and the guppies sing again while digging it out. Just as they find the treausure the Pirate and Parrot return!
The pirate makes them official pirates and they open up the treasure chest, revealing the treasure to be golden Sporks! The pirate tells them to come back to the ship and they use their golden utensils to have a nice meal. Deema asks what a pirate eats and Polly reveals the main course dinner: Map'nCheese! This makes everyone laugh as the episode ends...
Molly and Gil talk about the fun they had when suddenly Polly lands on the top of Gil's hat, causing it to sink down over his eyes and temporarily blind him. He tries to find Molly, and just what is on his head but he ends up wandering off screen as she giggles.
When Mr. Grouper tells everyone it's time to go outside, the Bubble Guppies are wearing pirate hats, but when the BG line up, the pirate hats are gone.
After lunch when the camera is moving to Molly and Gil, Nonny and Oona have switched lunchboxes.