After pushing a broom for centuries, Merlin's apprentice, Douxie, springs into action when the great sorcerer asks him to find the Guardians of Arcadia.

Douxie, Claire, Steve and Jim meet the legendary King Arthur and his sister, Morgana, in medieval Camelot — where being a troll is punishable by death.

With the future at stake, Douxie and Claire cling to the hope that Arthur and Morgana can reconcile. Meanwhile, humans are hunting trolls in the woods.

Merlin leads his ragtag crew on a quest to restore Excalibur and save Camelot. Elsewhere, Jim tries to convince Blinky that they're on the same side.

Morgana takes a new title — Mother of Monsters — and vows to usher in an age of reckoning. An epic battle begins in King Arthur's court.

Arthur seeks an alliance with the trolls of Dwoza as Gunmar begins building his army. Merlin and Douxie join forces to forge the amulet.

With the fateful battle underway, every hero must do their part to stop the Arcane Order, banish Gunmar and ensure that history plays out as it should.

After returning to the 21st century, Jim makes a surprising sacrifice ... and a familiar face joins the fight. The Green Knight finally reveals himself.

The Arcane Order pushes Douxie to make an impossible choice: save his friends ... or save the planet. Which will he pick? Only time will tell.