Beware the Longship is the twenty-eighth episode of Season 5, It takes place in Viking Age. When the Viking Chief launches an expedition to search for a milder climate, Oggy volunteers: the explorer will be named Head of the Colony! The cockroaches are determined to get there before Oggy and steal his longship…
Bob, the Viking leader, announces that the whole village will be on a journey to travel to a warm climate land. Everyone cheers in delight. Bob lays the map down which he shows a miniature longship that will travel on the ocean starting from the village, the light-blue colored land, across the three oceanic obstacles; the rough stormy waves, the giant sea serpent, and a large iceberg, to the gold colored land where he shows that the viking flag will be placed to claim it. All of the villagers move back as they are nervous except for Oggy and Jack whom Bob thinks that they are obliged. At the vent, Joey witnesses the whole things and evilly decides that to conquer that land only for cockroach kind with Marky and Dee Dee agreeing while being snowed as snowmen.
At the dock, Jack is loading large crates of consumables into the beautiful longship while Oggy in tears thinking that he will miss his love, Olivia. Jack smacks Oggy to snap out of his mind as they are following the leader's order. The cockroaches hide behind one of the crates and Joey implemented that the longship is loaded with food, much to their delight. While Jack was arguing with Oggy, the cockroaches quickly sneaks to the longship. Both Marky and Dee Dee climbs on board while Joey unties the rope. Suddenly, the longship starts to row, abandoning Oggy, Jack and Joey. Dee Dee waves goodbye. Jack angrily yells at Marky and Dee Dee and searches for an old, rickety longship which is located at a nearby dock. Joey swears that Marky and Dee Dee will get a punishment from him and temporarily joins Oggy and Jack. The cat duo starts rowing, catching up with Marky and Dee Dee.
Marky and Dee Dee in the beautiful longship, head to the rough waves where they move up and down, along the waves while Dee Dee becomes seasick and Marky is zapped by the lightning. Behind is Oggy and Jack in the old longship, who pierce through the waves and poor Joey gets blasted by the waves. As these competitors are travelling, Joey and Marky notices the giant sea serpent behind them. They maneuver through the underneath the some parts of its long body that shaped like an 'n'. The sea serpent sees another longship which Oggy, Jack and Joey are riding on and prepares by opening it large mouth wide just as Joey is scared. That longship just pierces through the whole body, covering Joey with serpent slime in the process. Both longships are heading towards the large iceberg. Marky steers away from the iceberg by drifting to the right and continues rowing straight with Dee Dee, while Oggy and Jack blast through the iceberg and poor Joey get beaten by the ice. Oggy and Jack catch up with Dee Dee and Marky. Joey angrily yells at Dee Dee and Marky about their dare of anyhow go off without himself. Marky and Dee Dee are concerned about getting punished by Joey and quickly row away, much to Joey's exasperation. Jack tells Oggy to paddle faster that Oggy shifts into high gear and zooms, overtaking Marky and Dee Dee. While in front, Joey thinks of something to get to that new longship. So, he uses a small ax to split the old longship into half with Oggy grabbing tightly on the halves with his hands and feet. But this idea backfires against Joey as that new longship which Marky and Dee Dee are riding in, just dash through in between the halves, flattening both Oggy and himself. Jack is angry at Joey and uses him to fish out a walrus which he uses as a longship stapler to fix the halves together. Then, both Oggy and Jack work together and paddle the longship, keeping the fast pace while Joey prepares to give Marky and Dee Dee a beating. As both longship collides on contact, Joey jumps into the new longship and brutally beats his roach pals who then follow his commands in dragon-boat style.
The longship competition is currently on the way; cats versus cockroaches, neck to neck. They both dodge large floating ice cubs, break through ice, and dash through penguins and polar bears. Joey attempt to throw the cat duo off track by throwing large crates of food at them but they do not faze them. Both longships enter into the fog and reach to the land at the same time. The cats and cockroaches want to put the flag but Oggy is the first to do it. As the fog clears, they notices that this village is familiar, much to their confusion. Jack checks the map and shows that they went around in a circle back to the starting point. Then, Olivia waves at Oggy and he waves back, happy to see his love and hugs each other much to Bob's disappointment. Episode ends.