Hey Arnold! The Jungle Movie

During the summer after 5th grade, Arnold and Gerald plan to make a humanitarian video to win a trip to San Lorenzo. They try to record themselves building a house out of junk for their friend Monkeyman, but a group of local homeless people storms in and destroys the improvised shelter, leaving Arnold heartbroken. The setback foreshadows the challenges they will face on their journey.

Helga compiles footage showing Arnold's good deeds and uses it to surprise him. The town is astonished by the collection, and Mr. Simmons announces that Arnold's video won the competition. Arnold, his PS 118 classmates, and Olga then fly to San Lorenzo.

On the plane to San Lorenzo, Arnold's pet pig Abner stows away in his backpack, adding a layer of comic trouble. The group remains unaware until the pig's presence becomes obvious.

Arriving in San Lorenzo, the group is greeted by Eduardo, an old friend of Arnold's parents. On a ship, Eduardo gives Arnold an amulet that is said to lead to the Green-Eyed People, the residents of the lost city. The amulet becomes their guide for the journey.

That night, Helga tries to confess her feelings to Arnold, but the boat is attacked by pirates. After Arnold's secret is revealed to the others, Gerald and the rest of the group shun him.

At the base camp, Eduardo reveals himself to be Lasombra, a mercenary who, with his men, imprisons everyone. He explains the contest was a trap to lure Arnold to San Lorenzo so he could locate the lost city and its treasures, and reveals the deal he made with Arnold, causing the class to shun him.

Hearing Arnold cry for his parents, Helga and Gerald escape to free him. They use Arnold's father's old journal to locate the city, but Lasombra anticipated this and had placed a tracking device on Arnold's green-eyed necklace.

Arnold and friends evade the lost city's traps while Lasombra pursues them, sacrificing many of his accompanying men to the traps. The group presses on toward the Corazón treasure.

Abner escapes and returns to Arnold's grandparents, who see this as a sign that Arnold is in trouble. They coordinate with Helga's parents after receiving an SOS from Phoebe, and plan to join the effort by flying to San Lorenzo.

The grandparents meet Helga's parents at the airport after receiving an SOS, and they fly a rental plane to San Lorenzo to join the others and help defeat Lasombra's gang.

Arnold and the others reach the city, which is populated by children due to a sleeping sickness that has left its adult population comatose for nine years. They locate the statue said to contain the Corazón, a treasure believed to hold the cure.

Lasombra corners the group, takes Arnold hostage, and steals the statue. He tries to force Arnold to open the statue with the amulet, but the statue's defenses shoot him with a poisoned dart, sending him over a cliff.

A mysterious man arrives and reveals himself to be the real Eduardo, explaining that the pirate on the ship earlier was him trying to rescue the group. Lasombra climbs back up from the cliff and gets into a scuffle with Eduardo, knocking the Corazón off the cliff before succumbing to the poison and dying.

The group returns to the city, and Arnold finally sees his parents, Miles and Stella, who are also infected with the sleeping sickness. Without the Corazón to release the cure, Helga uses her precious locket containing a photo of Arnold as a substitute. The temple releases the cure and the infected are revived.

Months later, life resumes at Arnold's grandparents' boarding house, now with Miles and Stella living there as well. Arnold says goodbye to his parents and heads off for his first day of 6th grade with Gerald, Phoebe, and Helga, with hints that he and Helga are a couple.