On a cold, New York City morning, Maria bids farewell to her friends, lamenting over the fact that they can't join her on a trip to visit her family in Puerto Rico. When her bus to the airport pulls away, everyone scrambles to gather their luggage; they'll be secretly following her to vacation in the warmer climate. At the last minute, Oscar learns of the "trick" they'll be playing, and heads off to the airport himself so that he doesn't miss out. Upon their arrival, Maria introduces Olivia to her family. On their way around the city, Maria does several double-takes, thinking she sees her Sesame Street friends, but upon a second look, they all turn out to be doubles. Meanwhile, Oscar's so-far disappointing experience takes a turn when he meets local grouch Osvaldo. That night, excited for her party, Maria calls back home, but saddens when she can't reach any of them. When she returns to the party, she's surprised to find her Sesame Street friends have come to her family home to help her celebrate.

After a big family breakfast, the gang heads out to see the sights. Bob and Linda bike to the beach, Big Bird observes oxen working in the field, and Luis finds himself fixing a water fountain in town with some taunting from Oscar. Maria and Olivia make a trip to the produce market while Bob sings about the plaza. Big Bird learns about a new type of frog that's native to Puerto Rico, and some local kids build sand castles at the beach with Luis and Susan.

Oscar and Osvaldo find themselves reluctantly cooperating when they go "trashing" around town. Oscar can't grasp the concept that "no" is the same in Spanish and English, so he keeps asking the locals the same question with the same answer. While he picks up onions and garlic to make juice for the picnic, Big Bird becomes frustrated with his attempts at trying to communicate with the birds in the area. Eventually, he learns that they've all been making Spanish bird sounds, and after a brief lesson, begins conversing with the nearby avian population. Wrapping up their end of the visit, Bob, Linda, and Susan board a bus to return home, while those remaining decide that the mischievous Oscar can make his way back with them later.

Everyone boards a boat for an excursion to a nearby island where they'll hold a picnic, just like Maria used to do when she was little. Oscar and Osvaldo have independently ventured to the island thinking they'll get some peace and quiet from the happiness of others, but they're distressed to find that they've been followed. Big Bird writes a postcard to Mr. Snuffleupagus, Maria sings about how nice it is to have returned, and Oscar is disgusted to find that, unlike fishing at home where he can count on catching garbage, there's only fish to catch in the Caribbean.

On their last full day in Puerto Rico, Luis and Big Bird prepare the town square for a festival. The vendors include a stand that repurposes junk into new items (much to Oscar and Osvaldo's chagrin), and a grouch pie-throwing game that involves the participants having pies thrown at them rather than, as expected, the reverse. Big Bird takes a group photo of Maria with her family, and, as night falls, David learns how to plena as the townspeople dance the night away.

Having bid her goodbyes to her family that morning, Maria and her friends fly back to a Sesame Street that has been lightly dusted with snow. Oscar tries to show off some grouchy phrases he learned from his Puerto Rican grouch companion, but he soon learns that he's been duped and that the greetings are actually friendly. Big Bird also has some wares to exhibit from his trip, all of them in groups of seven because that's how high he learned to count in Spanish. Back at the Fix-It Shop, Maria and Luis are distressed at the amount of work that has piled up in their absence, but Big Bird points out that it just proves how much they're needed.