While trying to prove that they are the Kings of Legend, Boomer and Brady accidentally bring Zadoc, an ancient evil statue, to life, consequently putting the entire island in extreme danger. The twins cede the throne to Lanny for the better of Kinkow and depart on a balloon voyage back to Chicago for good, until the balloon catches a wind and sends them plummeting straight to the Dark Side of the island.

Zadoc's minions capture Lanny and try to squish him with a huge rock. Lanny hands the throne back to Boomer and Brady. Mason goes after Zadoc and sees Boomer and Brady fight and defeat Zadoc and realizes that maybe they are the kings of legend.

The island is infested with giant mukarats after the kings offend the troll people responsible for keeping the creatures under control.

When the Kings' over-the-top spending causes a monetary crisis on Kinkow, Lanny has the islanders pay mandatory donations to the kings. Buying time until they find a better solution to fix the crisis, Brady and Boomer disguise themselves as bandits Sirocco and Sirocco Taco, stealing the kingdom's donations and returning the money to the public. With criminals on the loose, the Kinkowians start to get angry and the kings must find a way to restore the island's fortune, capture the criminals and win back their kingdom's support.

Boomer falls in love with a new girl, but the girl claims to be made out of Ice. Meanwhile, Lanny sends a servant to find Mason and Mikalya.

Boomer and Brady are flattered when a pair of cute Queens from the neighboring island compliment their latest ridiculous invention and ask them to be the Kings of Sununu. However, the Kings soon realize that the Queens and their kingdom are victims of a dumb-curse. In order to help cure the entire island of stupidity, Boomer and Brady must solve the Statue's riddle. When Brady gets the riddle wrong so the girls could still admire him and Boomer, the Statue puts the dumb-curse on King Brady, forcing Boomer to get help from Mason, Mikayla, and Lanny to solve the riddle by sunset or else they will be dumb-cursed.

Mason's brother Jason visits, but Mason isn't so welcoming due to an incident when they were kids. When the kings make Jason head guard, Mason quits and drowns his sorrows in eating. But when the Tarantula people try to roast Boomer alive, Jason cowardly runs off and it's up to Brady to convince Mason and his pregnant self to come back and save Boomer. When Mason arrives, he and King Brady are captured by tarantula people. The Jason's water skuter falls on two tarantula persons, and Jason falls on other two.

When Mikayla’s watchful eye keeps Brady and Boomer from getting into mischief, they host an island-wide search to find Mikayla a friend to keep her busy. The Kings soon regret the set-up when her new friend’s ‘beauty over safety’ mantra, puts all of their lives in danger.

Boomer and Brady find an ancient pocket watch.

Mikayla comes down with a fever and starts to turn into a Waka Waka Bug. So Boomer and Brady go to the Waka Waka Bug's hive to try to get the rare medicine to cure her.

Fed up with Brady's unusual habit of becoming a sleep ninja at night, Boomer impulsively moves out. But when his new landlord Charlotte turns out to be a former Tarantula Person and transforms Mason into a cold-blooded terminator, Boomer must turn to his brother for help.

Boomer opens the teen hotspot of his dreams and hires Brady as his assistant. When Boomer fires him, Brady spitefully opens his own club across the way inside a crypt upon being guided there by Lanny. When Brady performs a new song for the crowd with the lyrics having been provided by Lanny, the club is overrun by zombies that have been awakened by the song. Now it's up to Boomer to put his differences aside and rescue his brother.

Brady and Boomer must endure a King Challenge that tests their smarts, strength, and spirits. When Mikayla realizes the boys won’t pass the challenge, she agrees to help them, but the plan goes horribly wrong when Mikayla and Lanny are transformed into Boomer and Brady.

When Mikayla's ex-boyfriend Lucas (a pirate who broke her heart) refuses to participate in the official Kinkowian Dumping Ritual, the kings track him down and discover that Lucas looks just like Boomer. To help out his quest to finally date Mikayla, Brady makes Boomer impersonate Lucas and pretend to go through the official ceremony, but the plan backfires.

The kings want to introduce their subjects to their favorite holiday traditions of Christmas. They enlist the help of the islands giant elves to make the toys. Thanks to bad advice from Lanny, the elves revolt and the kings believe that their Super Christmas is gone only to be rescued by the jolly old elf himself.

Mikayla finally has enough of Brady's constant flirting and tells him that their friendship is at an end and it would be only professional from that point on. Later she and Boomer seem to be getting closer as their share a hobby of Kinkowian poetry slams. Brady in a fit of jealousy, outlaws the poetry trying to end the new friendship. And the fight is on.

When King Brady misses his favorite sneakers it's King Boomer that blames a monster that nobody has seen except him that he calls Mr Boogey. Nobody believes him, thinking he got rid of the stinky shoes. However Mason has been keeping a secret about the creature for years. After Mason is captured by the creature it's up to Boomer to prove Mr Boogey is real.

The kings are trying to act grown-up and impress the ladies only to find out their dates are luring them into becoming the source of power behind a fountain of youth.

When the castle mysteriously explodes, Boomer and Brady are taken to court and forced to relive their most embarrassing and heroic moments through video clips when they try to prove to the jury that they are not guilty of the unlikely event.

Lanny lures the kings into the domain of the Nanju Warrior tribe, which are beautiful young women who have mastered the areas magnetic fields and appear to nearly fly. Unfortunately for Lanny the tribe has high respect for the Kings of Kinkow and it winds up that Brady goes on a date with one of the leaders, Sabrina who is Mikayla's rival from their fight school days. When Mikayla refuses to duel with her Sabrina kidnaps Brady and cages him high in the trees in a trap that is about to fall to his doom unless Mikayla fights. While the two girls battle on land, tree and air, Boomer rescues his brother.

The kings discover that they are about to be forever remembered by their Chicago high school class as having thrown the worst party ever. Against Mason's advice they bring the entire class to Kinkow for the best Beach Party ever. Lanny switches beach signs and the party heads for the hunting grounds of the giant Kinkow Sand Maggot who has its own ideas for party snacks.

Brady tries to unite two conflicting tribes to impress Mikayla, but things didn't go as he planned to be.

The head chef quits when he is ordered by King Boomer and King Brady to prepare a steak cake when he was supposed to be making a very important meal for a giant ogre who is about to wake up from annual 10 year sleep, and when the ogre wakes up and demands food, the kings have to make a dish for him to save the island from his wraith.

When two moons appear, the kings meet the ghost of Malakai, the first king of Kinkow, who explains that an evil twin will destroy the island. After interrogating every twin on Kinkow, Boomer and Brady begin to turn on each other. Following Lanny's advice, the kings journey to the dark side to evil kings castle to sit on the evil throne and learn the truth. The prophecy comes true when the evil king is revealed, putting Brady under a spell and morphing him into evil Brady. With Mason and Mikayla in tow, Boomer heads to the dark side to save his brother and the island from sinking into the seas. Meanwhile, following a dream where she kissed Brady, Mikayla believes she may have a crush on him. Her friend Candace tells her that she does. Later when heading on with Boomer and Mason to save Brady from the evil king Kalakai, an evil Brady engages Boomer in a sword fight. Just before Brady can finish off Boomer, Mikayla gives him a long kiss, breaking him from Kalakai's spell.

Lanny returns from the Evil Castle and uses an Evil Thorn to make Brady evil.