During a blackout, King Julien declares the zoo to be under “Jungle Law”, which means that the Central Park Zoo has now possibly become "the Central Park Jungle"; non-civillized chaos ensues.
The lemurs are having a race to the bouncy castle but when King Julien tries to dive into it, he realizes that it is deflated. Kowalski is looking at all of the habitats through his binoculars and noticing that all of the electrical devices aren't working. The penguins hold a zoo meeting and Skipper at first claims that it's a space squid invasion, but Marlene points out that it's probably, with even Mason and Phil agreeing with her, as they take notice that the city (or at least Manhattan) is unusually dark.
The penguins promise to handle things in the zoo until the blackout ends, but King Julien takes charge and puts himself as the leader of the entire zoo during the blackout due to Jungle Law (he refers to Maurice as a certified jungle lawyer). Everyone but the penguins go along with Julien's plan, because Maurice has a briefcase. The penguins refuse to be a part of King Julien's kingdom. Skipper points out that Julien's plan will inevitably fail, and when it does, Skipper will tell Julien, "I told you so." Just as they are retreating back to their habitat, they realize that the zoo has turned into a madhouse with the animals fighting and running amok. King Julien gets kidnapped, Mort goes psycho looking for feet, and Bada and Bing are rampaging around stealing all the food they can find.
The penguins find King Julien hiding and scared of the chaos. He weakly defends that this riot is part of the "three successful minutes of Jungle Law." But before Skipper can tell him, "I told you so", Julien runs away, unwilling to admit that he was wrong and attempts to regain control. The penguins use Marlene and Maurice as part of their plan: Rico and Marlene go after the gorillas; Skipper and Private try to take care of Mort; Kowalski and Maurice attempt to save King Julien from Burt who thinks Julien is a peanut. When they have trouble solving the crisis, Skipper uses the problem he is handling to solve King Julien's problem so both problems are solved after the criminals are under control.
Eventually all is restored and as a "thanks", all of the other zoo animals want to catapult King Julien out of the zoo but before they can, Skipper tells them that it was Julien's plan all along to keep their minds off of the blackout.
The power comes back on and all is well, but only after the penguins catapult a watermelon into King Julien's head (because he let the credit go to his head).