Knighton is buzzing with festivities on the graduation day of the Knights Academy. In the middle of the party the vengeful jester, Jestro, releases the dangerous Book of Monsters and start making monsters that tear the place apart.
A magic blast from Merlok the wizard saved the day, but now Merlok is gone and Jestro is on the loose with the Book of Monsters.
Merlok 2.0 is glitching and the knights are not able to download their Nexo powers during training. King Halbert allows the Knights to transform his RV into a rolling Fortrex.
The king and queen are giving three people a tour of the kingdom. Meanwhile, Jestro and the Book of Monsters finds the Book of Chaos where Jestro summons up Beast Master to create chaos in one of the realm's city.
Jestro finds the Book of Fear and feeds it to the Book of Monsters. The jester then brings out spider-globlins and Whiparella, a monster who can find your deepest fears and can bring them to life.
When Lance is cast as the star in the new remake of "Ned Knightly and the Golden Castle", he doesn't anticipate Jestro and his monsters invading the set and ruining his starring role.
The Knights find themselves trapped in a maze looking for the Book of Deception. But will they actually get their hands on it, or will it keep deceiving them?
Leaving the maze with the real Book of Deception, Jestro feeds several books of the same kind to the Book of Monsters to create fake NEXO Knights where Sparkks is given the appearance of Clay.
Jestro and the Book of Monsters travel to the place where the evil wizard Monstrox did his evil deeds and find the Book of Destruction.
Aaron must figure out a plan to save all his friends. When Jestro was doubting his desire to destroy King Halbert, Beast Master feeds the Book of Revenge to the Book of Monsters where it increases the revenge motivation in Jestro and the Lava Monster Army.
The Nexo Knights return to the Knights Academy partly to get re-educated under the headmaster Sir Brickland and partly because Jestro and the Book of Monsters are after another spellbook that is located there.
The Nexo Knights attend the Gold is Good Ball hosted by Lance's parents in the extremely wealthy town of Auremville.
The Book of Monsters plans to consume a limited edition copy of a Ned Knightley comic book, which will guarded by the Nexo Knights until it is won at a costume contest at Knight-A-Con (this show's parody of the San Diego Comic Con).
On King Halbert's birthday, Jorah Tightwad decides to prove that the Tighty Knighties are better than the Nexo Knights at King Halbert's birthday tournament, using the Book of Envy as proof that they encountered Jestro.
The famed Knighton Chef Gobbleton Rambley has created a chili recipe so spicy, the Book of Monsters gains the idea to weaponize it.
The Nexo Knights send Clay on vacation to get some free time, unaware that Jestro and the Book of Monsters are on the trail of another evil spell book that is near where Clay is staying on his vacation.
Meanwhile, the Book of Monsters drags Jestro to Snottingham - one of the coldest places in Knighton where everyone coughs, has a runny nose and is generally under-the-weather.
Jestro and his monsters are in attack formation moving to pillage the town of Funnyton. But when they arrive, ready to tear into the place, they see that nobody's in town.
We finally REVEAL that Jestro has given the Book of Betrayal to...Clay. He tells Clay what it is and how Mike Knight used it. And it seems that the Book of Monsters believed it to be the final ingredient in some 'Master Plan.
Recapping from the previous episode, Clay hands The Book of Betrayal not because he was corrupted, but to exchange it for Jestro's freedom.
All is peaceful in Knighton. The knights are all working to keep the kingdom prepared to face their next threat. Which will come much closer than they think.
The Cloud of Monstrox and Jestro unlocks a mysterious Forbidden Power. What kind ofhavoc will they unleash? And can Merlok 2.0 and the NEXO KNIGHTS make the new COMBO NEXO Powers work?
Jestro and the Cloud of Monstrox encounters the sculptor. He helps unleash a horde of fierce garden gnomes on Knighton. What will the NEXO KNIGHTS do against this new enemy? Will their new COMBO NEXO Powers do the trick?
Jestro and the Cloud of Monstrox unleashes the Forbidden Power Ravaging Rot on Knighton! Turning everything into green gooey rot. But Robin has an awesome new invention that could help the NEXO KNIGHTS.
The NEXO KNIGHTS have their powerful shields stolen by Robot Hoodlum and his Merry Mechs. And something is coming to life in the Petrified forest, and it doesn't like knights. Can the NEXO KNIGHTS deal with this without their shields?
Villagers are being enslaved to dig out three ancient warriors whom the Cloud of Monstrox wants to bring back to life.
Monstrox learns where a Forbidden Power tablet is hidden, and he will do anything to get it.
The old Lava Monsters are back! And a Forbidden Power is in the middle of their new village of Burningham. But whose side are the Lava Monsters on?
Macy is mad! The three Harpies have kidnapped her mom Queen Halbert. The NEXO KNIGHTS use everything in their power to rescue her. But is kidnapping the real plan or is the Cloud of Monstrox after something else?
The Cloud of Monstrox is growing more and more powerful with every Forbidden Power Jestro inserts. The capitol of Knighton is under attack. The Fortrex is damaged and Clay is turned to stone. Dark clouds are truly gathering over the realm.
Party time in Knighton. The mood is down so the King decides to throw a party. In the meantime Jestro attacks the Fortrex, but he is confronted with the new Nexo Power "The Wedgie of Doom".
Using his Stone to Life magic the Cloud of Monstrox turns Clay into a living, fighting, breathing stone fighting knight. But will Clay use his forces to fight for good or for evil? Does he have a choice?
Clay wakes up in the poor town of Nothing Hill which literally has nothing. Will Clay remember who he is and what he is fighting for? His friends try to help him, but Jorah Tightwad and his Bots get in the way.
The Nexo Knights decide to use Clay to infiltrate the enemy camp but first Clay needs to learn how to be a good spy. Agent Shield, Jack Shield helps them with that.
Jestro and the Cloud of Monstrox builds a new stone army from giant building blocks to crush Knighton. The Nexo Knights try to convince Rockowski, a demolition expert, to help them.
Jorah Tightwad is digging for gold but finds the ancient Lord Krakenskull buried with his army. This stone army is exactly what the Cloud of Monstrox needs.
Clay Moorington the Nexo Knight has had enough of Monstrox, Jestro and their Forbidden Powers and decides to take the fight to them. But the Cloud of Monstrox is getting closer and closer to unleash his master plan.
Things are getting dire in Knighton. Jestro and the Cloud of Monstrox only need the Forbidden Power of Awesome Annihilation in order to reveal what's hidden in Mount Thunderstrox. It can't be nice.
The giant Stone Colossus is marching on Knighton. Ruina the witch tries to get to Clay, but the other Nexo Knights need him in their final defense of the realm. Which side will he choose? Family or friends?
The Cloud of Monstrox is inside of The Stone Colossus and it now stands in front of Knighton. The students of the Knights Academy are mobilized, the King and Queen are on the defence and the Nexo Knights are ready for the final showdown.