In the story, Avalon High Ellie's parents have moved to Annapolis, Maryland to work on their research regarding the Lady of Shalott and "Excalibur." Ellie is not excited about the move but is generally used to her parents being odd.
Upon going to Avalon High, she meets Will and they become friends. Ellie, however, suspects there is something more. Unfortunately, Will has a girlfriend named Jennifer that he believes is being honest and faithful. Jennifer, however, is cheating on Will with his best friend Lance. Ellie and Will are strangely familiar with one another especially since they just met.
As her days at Avalon High continue, Ellie starts to notice that things are a lot like the Arthurian legends her parents study. Ellie gets assigned a report on the Lady of Shallot by Mr. Morton, her English Teacher. She is paired with Lance, and together they discover the Order of the Bear. Inadvertently Ellie finds out about Jennifer and Lance's relationship. As she and Lance do their report, they discover information about the Order of the Bear, the sword owned by her parents, and the story of Arthur unfolding at Avalon High.
Ellie believes that she is Elaine, the Lady of Shallot. Mr. Morton (who is Merlin) and Marco (who is Mordred) also are aware of what is happening at the high school. Mr. Morton is a member of the Order of the Bear and is trying to keep Will (King Arthur) safe. Ellie is aware that the story will end badly for Will if Marco gets his way.
Ellie is conflicted about her ability to change Will's fate, because she is only the Lady of Shallot. According to the legends, she has no influence on the story except to fall in love with Lancelot and commit suicide at the end of the story. Neither one sounds particularly appealing to her. As Marco and the forces of evil begin their attack, Ellie discovers, in reality, she is the Lady of the Lake, the caretaker of Excalibur. Once she realizes this, she is able to give Will the sword. Together, they are able to fight and defeat Marco, stopping the evil.
Avalon High is mystery/fantasy novel written by Meg Cabot. The plot follows Ellie Harrison as she moves to Annapolis, Maryland. Ellie's parents study Medieval history, and named Ellie (Elaine) after Elaine of Astolat, who commits suicide because she was heartbroken. Ellie, of course, does not want to be named after a woman she deems weak. As she attends Avalon High, she meets Will, Lance, and and Jennifer. Will is believed to be a reincarnation of King Arthur. Ellie and Will become friends, but this relationship soon deepens to something beyond that. Will is certain that he has met Ellie before, perhaps in a different life. Although Will is dating Jennifer, Jennifer happens to be cheating on him with Lance. Ellie becomes more aware of Will's striking similarities in his life to the life of King Arthur, which includes his dysfunctional parents, who kick him out of the house. Will lives at Ellie's house, which prompts her parents to also notice that Will is basically King Arthur. A new revelation causes them to realize that Ellie is actually a reincarnation of King Arthur's protector, the Lady of the Lake.