Night Watchmen is the 3rd episode of Season 3. The cousins are left in charge of a toxic plant; while Jack sleeps, Oggy has to take care that anything wrong doesn't happen while the roaches cause chemical havoc!
Oggy and Jack are night watchmen in a nuclear power station. The roaches don’t want to miss that! They go in the control room, and in two ticks, all the warning lights turn red! Oggy chases after them and ends up in the heart of the reactor...Oops!Official Synopsis, 
In a nuclear power plant, the person in charge reminds Oggy and Jack that the radioactive barrels are highly explosive and instructs them to never cause any sort of tomfoolery, to which they agree. He then gives them the keys to the power plant and walks away, which briefly makes the two cats express giddy delight but quickly assume a mature, professional stance as he hears them. As he leaves in the pouch of a kangaroo outside the power plant, the nearby hazard sign flips to reveal the cockroaches hanging behind it, having somehow made their way to the plant.
However, Jack suddenly exhales tiresomely and brings out a beach chair which he then proceeds to sleep on, much to the ire of Oggy, who then hears three car-like honks coming from a forklift moving behind him, and it's being driven by the cockroaches! Horrified, Oggy grabs Jack's beach chair and tries to jump away from the forklift, but he is too slow to escape and gets knocked into the air by it, where he lands first, the beach chair second and Jack last. When he recovers, he notices in shock that the cockroaches are about to hit a motherload of radioactive barrels, so he gets to the barrels first before them and uses himself to shield them as the forklift rams into him.
The cockroaches laugh at this, back up the forklift and get on the fork, where Joey uses the forklift's controller to raise all three of them to a high platform with radioactive barrels. Not one to let the roaches get away, Oggy grabs the controller and presses it repeatedly to make the fork come down... on top of him. After the fork raises a bit, Oggy then gets on and presses the controller to raise the fork, but when he reaches the cockroaches, he realizes that the fork is still rising up and tries to stop it, only for the fork to squish him against the ceiling. The cockroaches mock him and run to an area where there are barrels with spigots on them.
Dee Dee then approaches a barrel with a spigot and turns on the spigot to spray out a pink/purple gas which he then digests and gets an oversized head as a result. Nonetheless, he shows off what the gas did to him to Marky and Joey, but the latter, unimpressed, detaches his nose and uses it to pop Dee Dee's head like a balloon, then mocks him along with Marky. Joey then approaches another barrel with a spigot and turns it on as he drinks a toxin which enlargens his buttocks, while Marky drinks from another barrel and ends up getting enlargened human-like feet with pink toenails. When Oggy manages to reach the cockroaches, he sees them all bloated up like balloons, still holding onto the spigots with their mouths. They then open floatie-like plugs and fly off like out-of-control balloons.
Realizing that he has to do something to catch them, Oggy runs to a barrel and drinks from it's spigot... but gets pink warts growing all over his body. Going to another barrel, he drinks from it's spigot but gets shrunk in size, and approaching yet another barrel, he drinks from it's spigot and is returned to his normal size. However, his tail gets so big that it pops and sends Oggy flying around, finally allowing him to chase the cockroaches in the air, but along the way, he gets burned by pipes producing fire from below, turning him into a roasted chicken just like in "French Fries". He then reverts to normal as he chases the insects through a pipe leading to a spinning fan, where they fly through it harmlessly while Oggy on the other hand gets it stuck on his nose. Nevertheless, the cat uses it as a biplane propeller to catch up with the cockroaches, but when he does so, he hits a pipe which then sprays out steam from the impact.
As the insects stand on a horizontal pipe laughing at Oggy, Joey then pokes a hole on the pipe and gets on it with his brothers as steam shoots them away into a gigantic barrel of acid, while Oggy slides down on the pipe and gets up as his face peels like the skin on a banana. Meanwhile, Joey and Marky are resting in the acid as if it were a swimming pool while Dee Dee jumps in from a diving board, swims to his brothers, spits out some acid and burps, gaining more eyes afterwards. The other roaches laugh at him, but soon succumb to the side effects of the acid and gain more body parts, but continue laughing like it's nothing.
Oggy manages to get on the enormous barrel, but first he dips his hallux into the acid and grows more of it, causing him to freak out, so instead he gets in the barrel through a circular door, manning a submarine with a robotic hand on it. As he snickers thinking he'll get the roaches for sure, he presses the yellow button on the control panel, thinking that will control the submarine's hand, but instead, he gets ejected out of the submarine and into the acid along with the chair, and ends up growing more eyes and limbs. However, Oggy snatches the cockroaches anyway, who now grow huge frog-like legs and use those legs to swim up and slam Oggy into the barrel's wall.
The now-mutated cockroaches then jump on the rim of the barrel and run along on it, followed by Oggy who tries to snatch them again, but before he can do so, the roaches leap backwards and fall into a smaller barrel of acid with Oggy, causing it to belch violently and reduce them into one slimy mass. Moving out of the barrel, Oggy approaches a washing machine, opens it and goes inside, where it spins and turns him and the cockroaches into underwear, a pair of socks and a winter hat. It spins again and turns them into a pig with three chickens, and then again which turns them into a familiar-looking group of aliens.
The washing machine spins one more time, and this time reverts all four of them back to normal. Oggy emerges from the washing machine, cackling as he clenches the cockroaches in his fist, and proceeds to tie them up, encase them in hard cement, chain the cement block up, throw it into a no-bug barrel, cover it up, drill a hole outside of the power plant, toss the barrel inside, cover up the hole with dirt and finish by pushing a huge muscular statue of himself over it.
Feeling satisfied with his work, Oggy goes back inside and sees Jack still sleeping, so he kicks the chair, finally waking Jack up, and tells him to get off the chair, which he does... so that Oggy can get on the beach chair for himself to take a rest from all of the trouble he went through to get rid of the cockroaches. As Jack prepares coffee, he is so tired that he unknowingly reaches out to a radioactive bottle and puts a drop of acid into his cup. As a result, the acid reacts and blows up the power plant, not to mention a chunk of the Earth, leaving Oggy and Jack charred.
The cockroaches, meanwhile, manage to get free from their underground prison and emerge from the ground, having survived the explosion with no burns, then go "whoa!" in awe and give a thumbs up. The episode ends with the cockroaches laughing as the iris out closes on an annoyed Oggy, whose eyes then fall off as his body crumbles.
- ↑ Oggy and the Cockroaches - Chatter Box (S2E156) Full Episode (published by OGGY on Sep 11, 2018, on YouTube. Accessed Sep 9, 2019.)