King Julien can't sleep so he decides to go on a milk cleanse to help, but after Todd is attacked by a horrible monster, King Julien's nightmares cause the kingdom to question him as...THE NIGHT CREATURE!
In the middle of the night, Todd had been attacked by some kind of fierce monster... and then King Julien wakes up with bloodshot eyes the next morning, convinced that the attack was just a bad dream until Maurice shown up and told him about last night's incident, freaking the king out as he noticed the disaster is an exact match to his dream; he slapped his adviser in the face several times to check if he's still dreaming, but Maurice informs Julien what happened was real and that Todd was with Dr. S at the moment. King Julien starts crying, thinking that Todd was dead, but Maurice points out that the young lemur survived because the beast that attacked him freaked out at the sight of his mother, Tammy. Attempting to calm himself down, King Julien downs a bottle of gecko milk, explaining that Masikura has him on some kind of "cleanse" on account of stress. Maurice was suspicious of this at first, as he wonders what in the world his majesty has to be stressed about, to which the king answered "I have been through a lot lately, Momo" in a tone that indicates that what happened the previous season is still haunting him... that, and his annoyance on account that the gecko milk is giving him indigestion as a side effect... but it seemed to have done its job, as he calmed down enough to think and agreed to come with Maurice to save Todd from Dr. S.
Once in Dr. S's cave, King Julien asked if Mort was responsible for what happened to Todd (Mort, wearing a wig, claimed he was innocent this time), and Dr. S claimed that he'd know what killed Todd would be clearer once he finished the autopsy, making Maurice point out, once again, that Todd didn't die, which forced the medic to take another look. Todd claimed he was alright save for a sore back... the father, Butterfish, claimed that his "little girl" was delusional and had to be put down, annoying the mother, Tammy, as she pointed out for the upteenth time that Todd is a boy... and Dr. S picks up the lemur child to examine said sore back, finding claw marks that he couldn't identify. Clover, showing up at that moment, recognized the claw marks as those of a "night creature". (Cue monster movie title cards, as she was in monster-hunter mode.)
Later that day, Clover explains night creatures to King Julien and Maurice with a book telling the true story about the curse of the night creature, which shows how handsome the king's ancestor, Julien II, had been... and how hideous and dangerous he was once inflicted with the curse, waking up in the middle of the night, turning into a monster, and hunting down lemurs and other creatures to eat; not even angry mobs could stop the beast! Then, Clover's ancestor, Grandma Rose-- being a cage fighter, occasional babysitter, and... above all else... a talented monster hunter-- stopped the night creature once and for all by killing it with a golden spear and burying it in a tomb that was sealed with a heavy stone. While putting the book away, Clover states her instincts is telling her that another night creature is on the loose, and it is up to her to live up to her family's legacy by killing it... but it would be easier if she knew who the monster is and kept anyone else from finding out as it might cause a panic.
Such a plan couldn't have had worse timing, as our King Julien's relatives had chosen that week of all weeks to visit to make a check in. Uncle King Julien had told King Julien's parents... Princess Julianne and Prince Barty... that their son had lost the kingdom to Koto, and spent the entire royal budget on a long war just to get it back. To that end, the prince and princess told King Julien that it was their duty to make sure things are running smoothly again, and that if they aren't they'd have no choice but to vote his uncle back on the throne!
Upon hearing that, King Julien empties several gallons of gecko milk that night to ease the resulting stress before ordering Clover to find the night creature and "wack it". Once his bodyguard leaves to carry out that order, King Julien heads to bed to get some much needed beauty rest, which was disturbed by a freaky dream within a dream in the form of a "double nightmare", with both visions holding a version of Todd attacking him fiercely as if getting revenge. Upon waking up for real, however, and checking to see if he really is awake, King Julien's night of terror was only beginning... he turned into the new night creature and gone savage, causing several attacks at the movies and a local Mango Tango bar. The attacks were quickly reported in the Daily Mango newspaper, and Xixi made a live "broadcast" on the broken TV for "Night Creature Watch", and also reported that Todd died (much to said lemur's annoyance, as he's still alive). Even Andy Fairfax was taking advantage of it, as he started selling "night creature protection cream" and other monster-repelling objects, as well as holding monster thrill shows with his partner Poncho. Clover, after having borrowed her grandmother's golden spear from a shrine, was annoyed at the con artists "making a game of all this", and drove everyone to return home as soon as possible with a town curfew just as Night Creature Julien was making another attack. In that same moment, Princess Julianne and Prince Barty were talking about whether or not they should leave early and give the crown to Uncle King Julien, but they decide to give their son a chance to prove himself instead, and do so by throwing a Haunted Jungle themed Masquerade Ball for him.
The next morning, Maurice rushed to his king's treehouse in the middle of a seasonal rainstorm only to find-- to his horror and King Julien's-- that Clover's spear was lodged in his majesty's hindquarters, acting as proof that what happened last night was real and the king really is the night creature. King Julien managed to pull the spear out of his body just before Clover could show up, making her think that he "found it" after she speared the night creature and "it" got away. After reclaiming her weapon, Clover states a totally random theory that the beast she hunted was an "Undead Zombie Night Creature" as the previous one could've come back to life to get revenge... such a theory only confused Maurice, but King Julien took advantage of Clover's paranoid idea to send her on a wild goose chase with it. Once Clover was gone, King Julien... believing himself to be a danger to his own people on account of his curse... practically begs Maurice to end his life, but the royal adviser refused on account that the king was his best friend, convincing him that they had to find another way.The next night was the night of the Masquerade Ball, and everyone was enjoying the cobwebs and other spooky decorations, though Uncle King Julien was freaking them out more then necessary when he stated how much loves a good scare, but our young King Julien, knowing the danger should his night creature side gets out on the dance floor, decided not to show up and asked Maurice to tie him to his own bed as tightly as possible. Maurice did what was asked of him, gave the king his gecko milk to help relax him, and vowed to remain at his side no matter what. Such a promise comforted King Julien so much that he nodded off almost instantly, and after a few hours, just as Maurice started to dose off keeping watch over his royal friend, King Julien transformed into the night creature again and broke free of his bondage, and would've harmed Maurice if the aye-aye hadn't managed to talk him out of it. However, just as it seemed that Night Creature Julien was able to listen to reason, the sound of the music from the Masquerade Ball got his attention and he gone ballistic and ran off. Realizing this could be a problem, Maurice rushed off to find Clover, who was realizing that the previous night creature was still dead and thus she was trying to make up a new theory about who the new night creature is. Maurice pointed out that the "night creature" was heading for the Masquerade Ball, and Clover ran off on the hunt before she could be told that it was her king. Back in the Masquerade Ball, Prince Barty and Princess Julianne were having a great time for the event they threw for their son despite it having details that disgusted them such as Mort's cage-dancing performance, the other guests wearing masks that aren't even made of gold, the catoring tasting terrible enough to make them throw up, and... worst of all... the guest of honor, the king, being a no-show, but Uncle King Julien, while comforting his brother-in-law and sister, seemed ecstatic about that, claiming he could already feel the crown back on his head and (oddly) getting popcorn to watch the show when Night Creature Julien attacked the event and set off an angry mob that was lead by Clover and Butterfish (who claimed he was getting revenge for the "death" of his "step-daughter", and showing his compassion under the confusion and rage). Just as Night Creature Julien was cornered, however, and before could be speared again, he was "trapped" in a cage dropped on him by Mort and Princess Julianne. Clover was thrilled by that, until the princess told her off for sharing her late grandmother's paranoia on account that there is no such thing as a "night creature". Prince Barty then explains, much to the shock of the entire kingdom, that this "night creature" is their son, King Julien, and that he and his mother's branch of the royal family has a really bad gecko milk allergy that makes him take this unpleasant form. Maurice was shocked that this didn't happen sooner, as the king had been drinking gecko milk all week, and Prince Barty claimed that their son is lucky as he always travels with his travel scepter, which contains the antidote for this allergy-- a simple peanut-- in a secret compartment. Once King Julien was given his "medicine" and quickly returned to normal, he explained he was drinking gecko milk because Masikura gave it to him for his diet, but Masikura claimed she'd did no such thing. Mort was accused next after that, but Mort shown the letters from "Masikura" politely asking to deliver gecko milk to the king... the soothsaying chameleon, annoyed, gets a closer look at the letters and points out the obvious fact that Uncle King Julien's name was crossed out and her name was written in place of that with a crayon! Wasting no time with that note, as nobody "poisons" his son and gets away with it, Prince Barty drops a cage on his escaping brother in law, and... to make sure the punishment fits the crime... King Julien orders Mort to "milk that bad lemur" so that the family allergy could turn him into a night creature; an order that Mort carries out with pleasure. After that, Prince Barty and Princess Julianne, despite thinking their son is a "pickleheaded jollywag" at times, decided to let him keep the crown as they all continued to enjoy the Masquerade Ball, in which the true King Julien leads the remainder of the celebration with a new dance move he made up called the "Night Creature".