During the graduation ceremony for the new Knights of Knighton, Jestro the jester is ridiculed for his terrible, uh, jestring. Distraught, he's seduced by the powerful and evil Book of Monsters until Merlok the Magician tries to stop Jestro by using his most powerful magic spell.

After a magical explosion, Jestro discovers that he still has the Book of Monsters and together they decide to attack and destroy the Kingdom. Their monsters seem like too much for the new Knights of Knighton until an old friend emerges in a new form.

When Jestro and the Book of Monsters start using their monsters to ravage the countryside, the Knights get an awesome new HQ to fight him, the mighty, powerful Rolling Castle known as the Fortrex.

Clay and Lance tussle over who should lead the Knights and protect the King who's toddles off on a PR tour of the kingdom. While fighting off Jestro and his monsters, Lance realizes that nobody knows the Knights' Code like Cla.

The Knights explore a strange forest looking for a Book when Jesto unleashes the Book of Fear on them and a new monster, Whiparella, uses her minions to induce the Knights' worst knightmares.

Jestro and the Knights are both trying to get the Book of Deception. But the book has used its powers to create a powerful maze in the Hill Country, near Axl's home, and it's a race to complete the maze and get the Boo.

When the Knights of Knighton can't defend the outer villages of the kingdom, a mysterious Black Knight appears to take on Jestro and his monsters. Who is he really and is he a new ally or a new foe?

Jestro uses the baddest book yet, the Book of Destruction, to make monsters that capture the Knights one-by-one so that he can turn his attention to attacking the King's Castle.

Seeing Jestro's monster army about to destroy the King's Castle, Aaron rides off to gather his cohorts. In the meantime, the King and Queen bravely go out to defend the city against the monster menace. Is this the end of Knighton?