Allie Pennington, the daughter of two medieval literature scholars, transfers to Avalon High and becomes involved in a prophesied re-staging of Arthurian legend. Allie meets various new people who she later discovers are the reincarnations of figures from the legendary Camelot. She befriends two boys: Will, a quarterback and most likely the reincarnation of Arthur, and Miles, who has psychic flashes and is most likely the reincarnation of Merlin. There's also a third boy, Marco - Will's stepbrother, whom Allie believes is the reincarnation of Mordred and determined to kill Arthur (Will) – which would send the world into another dark age.
Allie gets a project from her teacher and Miles is her partner. He comes over to study but they need help from her parents who wrote the book they are studying on.
As Allie gets closer to her classmates, she starts to experience visions of King Arthur and becomes better friends with Will. She starts to suspect that the legend of the prophecy is true. She discovers at a party that Jennifer (Will's girlfriend) and Lance (his best friend) are having an affair behind Will's back. She fears that if Will found out he would suffer the same fate as King Arthur and meet his downfall, while her own feelings for Will start to grow. Together, Miles and Allie discover the day King Arthur is prophesied to return.
Will suffers from morale blows both in school and at practice that shake his confidence before the big game, which Will has to win in order to gain a scholarship to please his overbearing father. Allie tries to tell Will about Jennifer and Lance's affair but is constantly interrupted, so she enlists the help of Mr. Moore (Allie, Will, Lance, Miles' medieval history teacher) to protect Will.
On the night of the game Will arrives early to school and sees Jennifer and Lance together and takes off; Allie and Marco give chase. Finding Will at the forest where they had previously spent time together, she tells him that he is King Arthur, but he takes it as a metaphor about him returning to the game. Allie and Miles then attend and watch as Will returns to the game as the prophesied eclipse and meteor shower take place. At half time, Lance apologizes to Will for the affair but Will instead gives his blessing for Lance and Jennifer to be together, forgiving them both. Will then asks to meet Allie after the game, but he disappears from the game. Allie and Miles go in search and for the first time, Miles uses his psychic power at will to find him.
Going to the school theater, they find an injured Marco outside and Will inside the theater, again Allie tells him the truth of his identity. Mr. Moore arrives and reveals that he is really Mordred and that Marco's father was actually a member of the Order of the Bear before he died. Ever since he died, Marco has sworn to continue his fathers job to protect Arthur (Will), and had been trying to gain Mr. Moore's trust. Mr. Moore (Mordred) then attacks the group. Allie grabs a prop sword to stop Mr. Moore, but it transforms into Excalibur, revealing that she is the real reincarnation of King Arthur. Mr. Moore and Allie duel in an alternate reality, where Will, Marco, Miles (Merlin), and Lance (Lancelot) are also present and fighting. With the help of Merlin, Allie defeats Mordred.
Back in the theater they are able to escape and Mr. Moore is detained. Will then returns to the game and promises to talk with Allie afterwards, and he proceeds to win the game. Miles now embraces his powers and becomes more social which gets him a girlfriend. At the end of the game, Will kisses Allie and they leave the game together hand in hand.
All the characters gathered together at the round table dressed as their legendary counterparts. The movie closes with Allie riding along the beach on a horse.Britt Robertson as Allie Pennington/King Arthur
Gregg Sulkin as William Wagner
Joey Pollari as Miles/Merlin
Devon Graye as Marco Campbell
Molly C. Quinn as Jennifer/Guinevere
Christopher Tavarez as Lance Benwick/Lancelot
Steve Valentine as Mr. Moore/Mordred
Don Lake as Mr. Pennington
Ingrid Park as Mrs. Pennington
Craig Hall as Coach Barker
Anthony Ingruber as Sean
The Fire Theft - Chain
Jordin Sparks - Battlefield
Play - Destiny
Filming took place in Auckland, New Zealand, from May 3 to June 3, 2010. Bethells Beach was used as a location for full-armour battle sequences. Mechnology Visual Effects created 134 visual effects shots for the production.
The film's premiere was watched by 3.8 million viewers.