The Setup & Betrayal: David Ticoule (Philippe Lacheau), facing immediate termination from his job after causing a disastrous animal escape at the zoo, makes a corrupt deal with boss Jeffrey Malone (Jean Reno). Malone tasks David with traveling to South America to retrieve a secret crate. To ensure he isn't caught by customs officers like Raymond (Alban Ivanov), David uses his dim-witted friend Stéphane (Julien Arruti) as an unwitting pawn, placing the crate in Stéphane's cabin.
The Breakout: On board the cruise ship, Stéphane opens the crate, expecting smuggling contraband, but finds a newborn baby Marsupilami ("Bibi"). The baby creature forms an immediate bond with David’s son Léo. However, a video of the baby Marsupilami performing martial arts maneuvers accidentally leaks online, going viral.
The Climax on the Cruise: Mercenaries hired by Malone assault the ship to recapture the creature. Pablito Camaron (Jamel Debbouze) arrives, revealing that Malone intends to harvest the Marsupilami for private black-market collectors. During a chaotic confrontation on the ship's upper deck, David abandons his chance to secure his corporate job, publicly exposing Malone’s illegal trafficking network to journalist Hélène (Reem Kherici).
The Return to Palombia: David, Tess, Léo, Stéphane, and Pablito hijack a speed boat and navigate into the deep Palombian rainforest. In a climactic showdown against Malone's remaining poachers, the adult Marsupilami parents emerge from the canopy, utilizing their prehensile tails to wipe out the mercenaries.
Ending & Hidden Meaning: David safely returns baby Bibi to its parents. Tess and David officially reconcile, agreeing to rebuild their marriage. Upon returning to France, David quits his zoo accounting job to start an animal sanctuary alongside Pablito and Stéphane. The post-credits scene reveals Jeffrey Malone stuck in a Palombian jail cell, constantly tormented by wild coatis. The post-viewing insight reveals that the entire trip was never about saving David's corporate career—the Marsupilami deliberately allowed itself to be found to reunite David’s broken family.