While picking mushrooms in the forest, Merlin is attacked by an enormous, angry-winged beast. The fierce creature has the head of an eagle and the body of a lion. Merlin thinks he's done for until a stranger appears out of the forest and fights it off with a sword. However, when he strikes the monster his sword breaks, so he picks up Merlin and they run for cover. They dive under a fallen tree, and the beast, unable to reach them, flies off. Merlin's rescuer introduces himself as Lancelot. When Lancelot winces in pain, Merlin realizes he's injured.
Merlin takes Lancelot to Gaius, who sees that the wounds are superficial. Meanwhile, King Uther and Prince Arthur see a nearby village that has been destroyed by the same beast. Uther wonders what could have caused such destruction. Arthur describes what the villagers saw and says it took no livestock, just people. Meaning, it's developed a taste for human flesh. Uther orders Arthur to put sentries at all the outside villages and the lookouts on full alert. They want Camelot to be ready in case the beast attacks.
Lancelot tells Merlin that he came to Camelot to fulfill his lifelong dream of becoming Knight of Camelot. However, he thinks he has no chance. Merlin couldn't disagree more, having seen him fight. He takes Lancelot to where Arthur is holding knight tryouts. They watch a candidate take the final test: to last one minute against Arthur in a duel. The man fails in seconds. Afterward, Arthur tells Merlin he's discouraged that so many are failing and wonders how he'll defend Camelot. Merlin tells him about Lancelot. When Arthur says only those of noble blood are eligible, Merlin lies, saying Lancelot is nobility. Arthur agrees to see him tomorrow.
When Merlin asks Lancelot about his heritage, Lancelot says he's not of noble blood. Merlin and Gaius tell him about the First Code of Camelot, which devastates Lancelot. Later, Lancelot tells Merlin that his village was attacked by raiders when he was a boy. He saw his mother and father murdered along with the rest of the town. He escaped, the only survivor, and swore to never be helpless in the face of tyranny again. He devoted his entire life to combat training and when he was ready to try for knighthood, he came to Camelot. Now, he feels all that effort was wasted. Merlin vows to make it right.
Merlin borrows an encyclopedia of noble seals from the castle library and using magic, creates a forged seal of nobility for Lancelot. He shows it to Lancelot, who's reluctant to go along with the scheme because it goes against everything a knight stands for. However, Merlin convinces him that he just needs a chance to prove his worth. Later, Gwen (Guinevere) fits Lancelot for his chain mail and they are instantly taken with each other. Gwen, who's in on the secret, tells Lancelot that she's proud of what he's doing, as she thinks everyone should have a chance to be a knight.
In his new armor and accompanied by Gwen and Merlin, Lancelot presents his seal of nobility to Arthur, who sucker punches him when he's bowing. Arthur tells him his reflexes are slow and he'd be dead if this was a battlefield, then says to come back when he's ready. Lancelot proclaims he is ready. Arthur says then he can start by cleaning the stables. Merlin gives Lancelot a thumbs up to assure him he's made his first step toward knighthood.
Gaius is incensed when he learns Merlin forged the seal, but Merlin defends his actions, saying the Code of Camelot is unfair and it's the only way he can repay Lancelot for saving his life.
The next day, Arthur finds Lancelot sharpening weapons and tosses a broomstick at him. This time, Lancelot reacts in time and catches it. "Not bad," Arthur says, and takes a stick for himself. He tells Lancelot to "kill him." At first, Lancelot doesn't understand, but Arthur goads him into a duel. The two spar in front of wary townspeople and Lancelot puts up a valiant fight. Once Arthur has seen enough, and gotten in one last good blow, he congratulates Lancelot for making basic training.
Alarm bells sound, announcing an influx of refugees from another village that was ravaged by the monster. Uther deduces that it's moving towards Camelot and orders Arthur to prepare the knights. Meanwhile, Gaius searches his books to try and find out what the creature is, but comes up empty. The next morning, Arthur tells Lancelot they're moving up his test of knighthood. At testing, Lancelot holds his own in his duel with Arthur until the prince flattens him with a vicious blow. However, Lancelot is only feigning unconsciousness and attacks Arthur when he isn't looking, forcing him to concede.
That night, with pomp, circumstance and flowing ale, Lancelot is knighted Sir Lancelot by King Uther. Even so, Uther is suspicious of Lancelot's claim to be the fifth son of a king whom he knows to have only four. He sends Lancelot's seal of nobility to Geoffrey of Monmouth, the court genealogist, to verify its authenticity. Meanwhile, as Arthur and Lancelot bond as peers, Merlin tells Gwen he thinks Lancelot fancies her. He jokingly asks who she'd choose if she had to choose between Arthur and Lancelot. Gwen says she'll never have to make that decision.
The next morning, Geoffrey of Monmouth tells Uther the seal is a forgery. Lancelot is arrested and brought before Uther, where he admits to lying about his nobility. Uther deems him not worthy of the honor bestowed upon him, adding that he never will be. He orders Lancelot thrown into the dungeon. Arthur contests his father's decision, saying that while Lancelot's deception was inexcusable, he only wished to serve. Uther doesn't budge, asking Arthur how he can trust someone who's lied to him. Guilt ridden, Merlin visits Lancelot in the dungeon to apologize, but Lancelot assures him he's not to blame, as he willingly went along with the plan.
Gaius discovers that the monster terrorizing the villages is a griffin, a creature previously thought to be mythical. As if on cue, the griffin attacks Camelot. Arthur and his royal knights rush to fend if off but it proves to be indestructible. From his cell, Lancelot can only hear what's happening. His spear destroyed, Arthur fends the griffin off with a torch and it flies away.
Uther praises Arthur for fending off the creature, but Arthur worries that it's still out there. Uther says they should hunt it down. Gaius tells Uther that the monster is a griffin, a creature of magic, and therefore can only be defeated by such. Uther, who detests magic so much that he's banned it from the kingdom, dismisses Gaius. However, Arthur says there's validity in what Gaius is saying, as their weapons were useless against it. Even so, Uther won't be swayed and orders Arthur and his knights to track down the griffin and kill it.
Later, Gaius tells Merlin that Uther is sending Arthur to his death. He tells Merlin that he must use magic to defeat the griffin and save Arthur. When Merlin is surprised that Gaius is telling him to break Camelot's law and use magic, Gaius says it is his destiny, the true purpose of his magic. Merlin becomes panicked, thinking he's not powerful enough to kill the griffin, but Gaius assures him that he is.
Arthur visits Lancelot, angry at himself for being so stupid, as Lancelot doesn't look or sound like a knight. Contrite, Lancelot says he's sorry. Arthur is sorry too, because "Lancelot, you fight like a knight." He admits Camelot needs him to fight the griffin but Uther forbids it. Lancelot recalls his own battle with it, saying there's merit to the theory that magic must be used to kill it. Unbeknownst to Uther, Arthur tells Lancelot to leave Camelot and never come back. Lancelot says it's not his freedom he seeks. He only wants to serve with honor. Though Arthur's regretful Lancelot can't fight with him, he orders him to leave before he changes his mind.
Gaius and Merlin find a spell to enchant a spear so it will be powerful enough to kill the griffin. Merlin holds the spear and focuses on it. He recites the incantation, but nothing happens. Gaius assures him that he has plenty of time to get it. Lancelot visits Gwen and asks her to provide him with weapons and armor to fight the griffin. She begs him not to go, but he sees it as his duty. Gwen tells Merlin and Gaius of Lancelot's plan to battle the griffin. Merlin rushes off to join him, all while still trying to enchant the spear.
Meanwhile, Arthur and the knights have arrived at the griffin's lair. However, without the aide of magic, it makes mincemeat of them and badly wounds Arthur. Lancelot and Merlin hear the screams of the knights and find them scattered. Lancelot and the griffin charge each other and Merlin knows it's now or never. He focuses on Lancelot's spear and says the incantation once. Nothing. Twice. Nothing. He tries again. Finally, with seconds left before impact, Lancelot's spear glows with light. The griffin jumps to attack and Lancelot pierces its heart with his enchanted spear. Arthur wakes, sees Lancelot and the dead griffin. Merlin runs off before he's spotted.
Merlin tells a relieved Gaius he did it while a proud Uther commends Arthur for slaying the griffin. However, Arthur credits Lancelot with the deed and invites him in. At the sight of Lancelot, Uther becomes enraged that Arthur defied him and orders Lancelot out of the room. Arthur says Lancelot saved his life and fought with honor. When Merlin arrives, Lancelot says he knows he used magic to defeat the griffin and promises to keep his secret safe. Uther and Arthur argue over whether or not to restore Lancelot's knighthood, but Lancelot can't stand to be the source of their fighting. He asks for their forgiveness and leaves Camelot.
Gwen sadly watches Lancelot ride off, as Merlin and Gaius do the same. Merlin tells Gaius that he was right, perhaps he should have never gotten involved. However, Gaius says that on the contrary, he was wrong, that both Lancelot and Merlin needed each other as their destinies were entwined. As he watches Lancelot depart, Merlin says prophetically, "Until next time, Sir Lancelot."