Allie the daughter of two medieval literature scholars, she transfers to Avalon High and becomes involved in a prophesied re-staging of Arthurian legend. Allie meets various new people including, Miles, Will, Jennifer and Marco. Who she later discovers are the reincarnations of figures from the legendary Camelot. She befriends Will, a quarterback and the most likely the reincarnation of Arthur, and Miles, who has psychic flashes and is most likely the reincarnation of Merlin. She also meets Marco - Will's stepbrother, whom Allie suspects is the reincarnation of Mordred and determined to kill Arthur (Will) thus sending the world into another dark age.
As Allie gets closer to her classmates, she starts to experience visions of King Arthur and becomes better friends with Will. She even begins to suspect that the legend of the prophecy is true.
On the night of the game Allie and Miles attend and watch as Will as the prophesied eclipse and meteor shower take place. At half time, Will then disappears from the game. Allie and Miles go in search and for the first time, Miles uses his powers to find him.
Going to the school theater, they find an injured Marco outside and Will inside the theater, Allie then attempts to explain truth of his identity to Will. Mr. Moore arrives and reveals that he is really Mordred and that Marco was actually a member of the Order of the Bear who was sworn to protect Arthur, 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 Mordred's forces. With the help of Merlin, Allie defeats Mordred.
Back in the theater Allie and the others are able to escape while Mr. Moore is detained. Will then returns to the game and promises to talk with Allie afterwards, and he proceeds to win the game. At the end of the game, Will kisses Allie and they leave the game together hand in hand.
Later, Allie and the others gather together at the round table dressed as their legendary counterparts.
- Elaine is renamed Allie in the movie.
- Allie is reincarnation of King Arthur, although Mr. Morton and Marco thought she was the Lady of Shallott (also known as The Lady of the Lake).