When King Arthur and the Knights of the Round Table are defeated by the Warlords and then Queen Guinevere is later captured by the foes, the wizard Merlin recruits a group of football players (and their equipment manager) from the present day to protect Camelot and save the queen.

Having repelled the Warlords once, the Knights of Justice continue to make their way with Merlin's help toward where Morgana holds Guinevere. Morgana is aware that King Arthur and his knights are still imprisoned so those approaching are strangers. She succeeds in capturing Lance and Trunk, causing Arthur to travel to her castle to rescue them as well.

Lady Elaine warns Arthur and his Knights of a premonition she recently has dreamed, foretelling the quest to gain the Key of Truth to be a trap.

Merlin's falcon reveals to him that the key Arthur alone can use to free King Arthur from the Cave of Glass has been found. Merlin creates an impenetrable tunnel to send Arthur, Gallup, and Phil most of the way to retrieve it, but Morgana is aware of the extreme use of magic so reasons whom has used it and why. She sends Lord Viper and the Warlords to Crownhorn, the village it's ended up near, just after the knights stand up for Orin, a villager in a misunderstanding with an army of gnomes then are offered hospitality by him and his wife Kate. Suspecting the knights are in the home of Orin or a neighbor, they kidnap Kate with orders for Orin to bring a knight to him to ransom her.

The magician Cryslin requests Arthur's help in freeing her father, King Arthur's sorcerer friend Rigis, from a sea serpent. He accepts and goes with Lance, Tone, Breeze, Trunk, Gallup, and Everett, but Everett's falling off the wagon she turned invisible reveals them soon after. The Warlords attack the knights near a village where a group of boys assist them in the victory. But the men in the village fear the Warlords, who vow vengeance on them. The knights stay behind to defend it against their promised attack while Arthur, despite learning from Crislin that she was leading him into a trap in exchange for her father's life, goes with her anyway to defeat the serpent and rescue Rigis.

Breeze is wounded during a battle with the Warlords. Determined to let none of the other Knights of Justice come to harm at his side, Arthur challenges Viper to single combat, and has Zeke deliver it with other Warlords as witnesses so he'll have to keep his word. But everyone else's misgivings about Arthur's plan prove well-founded when Viper employs treachery in the duel.

Breeze is wounded during a battle with the Warlords. Determined to let none of the other Knights of Justice come to harm at his side, Arthur challenges Viper to single combat, and has Zeke deliver it with other Warlords as witnesses so he'll have to keep his word. But everyone else's misgivings about Arthur's plan prove well-founded when Viper employs treachery in the duel.

When King Arthur and the Knights of the Round Table are defeated by the Warlords and then Queen Guinevere is later captured by the foes, the wizard Merlin recruits a group of football players (and their equipment manager) from the present day to protect Camelot and save the queen.

Tone builds a hang-glider for Arthur, Lance, Darren and Trunk to invade Castle Morgana.

Arthur and Breeze are attacked by the reincarnation of Viper.

Tone and Merlin share a dream that, during a battle, Tone falls through a tree and finds himself in a hospital where he sees his mother in a coma which it's believed his presence could help her recover from. Merlin realizes it was a true vision since he had another of the same tree, the new location of the Key of Truth for King Arthur - which can actually be used along with another to transport the knights home, if briefly. But the tree is inhabited by the giant Grinlap. Arthur, Tone, and Darren with his own key set out to retrieve it so Tone can see his mother awaken, but the Warlords don't intend to let them have another key...

King Arthur receives a message from an old friend who is being held captive by an enemy of Camelot; the knights are tasked with rescuing the friend and bringing the enemy to justice.

When Merlin is asked why Bog Lake is boiling, he learns that the key Lance can use to free Sir Lancelot is within. Tone creates a portable shed with scuba equipment of vines so Artur and Lance can search for it. The three, Wally, Brick, Breeze, and Lug avoid the Warlords on their way out thanks to a Merlin's decoy, but Morgana learns of the key about the same time the Warlords realize the trick. The Warlords attack just after an underwater chasm opens and the key falls in, and cut Lance's scuba so he topples in as well. The knights believe he has died, but Morgana realize he's alive in an underground cave. But she and Viper, determined to claim the Key of Truth, don't intend to let him stay that way...

Tyronne and Everett are sent on a mission to retrieve a powerful weapon called the Blade of Betrayal; their mission takes an unexpected turn when they are ambushed by a group of bandits and separated from the other knights.

Sir Tone feels discouraged after a series of unsuccessful battles against the forces of evil.

Despite Darren, Wally, and Brick fighting alongside him, Arthur is effected by Blinder in battle long enough for Hammer to wound him and Blackwing to steal Excalibur. Wally blames himself for not being able to protect him from every harm, so moodily avoids the others - then accuses the others of blaming him for their own failure. Then he defects to join Morgana, giving her Merlin's wand.

During a battle too early to tell which side is winning, the Warlords abruptly retreat when a lunar eclipse begins. Merlin remembers too late that it has transported the three attained Keys of Truth through an unspecified time in the twentieth century, which Morgana has told the Warlords. The portal is Grinlap's tree, so Arthur, Darren, and Tone return to time-travel again and reclaim the keys, but the Warlords are ahead of them. Annoyed by their confrontation in his home, Grinlap watches the Warlords go through the portal then throws the knights in. They end up in the 1950s, when an amusement park with a Camelot theme is in the area. While the Warlords cause havoc some are aware of and some aren't, the knights try to avoid attack by them and track down the keys.

Knights are tasked with rescuing a group of prisoners who have been taken to a mysterious island.

Merlin dreams that he is attacked by the monster of Fear Island, the one place where his magic cannot function and where Tone's key is. He sends the Knights of Justice there with the warning that the creature's hideous appearance will disintegrate any who view it and they must use all their resources and wits to be the first to survive the isle. Seeing them setting off and guessing why, the Warlords attack as expected from sea and are repelled - but only because they held back to attack them again on the island, intending to destroy them before the reach the beast's castle. The knights make it through, but the danger within is so strong even the magic they call upon in battle is limited...

Merlin discovers that an important magical book has been stolen from Camelot.

Morgana returns to Camelot with a new plan to defeat King Arthur and the Knights of the Round Table.

The knights are tasked with finding the book and returning it to Camelot.

The Knights of the Round Table face an army of Ice Warriors led by a powerful sorceress named Vanda.

As they search for the book, the knights come across an enchanted tower guarded by a fierce dragon.