A young girl named Kayley desires to become a knight of the Round Table like her father Sir Lionel in the kingdom of Camelot and wishes to accompany him when the knights are called to a special meeting with King Arthur, but he kindly objects that she is too young and promises to take her someday. When the knights arrive at Camelot, Sir Ruber (who has gone mad with power and seeks riches from his position as a knight of the Round Table) attacks Arthur then mortally wounds Lionel. Ruber is repelled by the other knights after Arthur strikes him down with Excalibur.

After Lionel dies, Kayley must learn to live without him. Inspired by her father's bravery, she spends ten years tending to her family farm. Now a young woman, Kayley is still much of a dreamer and still wishes to be a knight, much against her mother Julianna's wishes.

Meanwhile, the knights again gather with King Arthur and Merlin to discuss the era of peace among the kingdom when a Gryphon flies in, attacks and wounds Arthur and takes the sword Excalibur. Merlin summons a falcon with silver wings called Ayden to face the gryphon. After a furious fight, the gryphon drops and loses the sword in the Forbidden Forest. He reports this to Ruber. The call goes out across the land that Excalibur had been stolen, but Kayley's mother forbids her to go out after it. Shortly thereafter, Ruber comes to pay Julianna a visit, planning to use her to gain access to Camelot and introducing a magic potion that he had gotten that combines his men (and by accident, a chicken) with an assorted array of weapons. During the festivities, Kayley manages to free herself and escapes capture by fleeing to the Forbidden Forest, whose enchanted plant and animal life prevent Ruber's army from following her. The chicken, now named Bladebeak, is ordered to follow Kayley and report her whereabouts to Ruber.

While lost in the forest, Kayley comes across Garrett, a handsome and blind hermit who wishes to be alone. After some persuasion, he grudgingly helps Kayley find Excalibur. Guided by Ayden, they manage to find the scabbard of the sword in the footprints of a giant. As they make their way into dragon infested mountains, they come across a conjoined two-headed dragon - the sophisticated and intelligent Devon and the boorish but loyal Cornwall. Thanks to the bullying from the rest of the dragons due to their differences and their inability to fly, they want nothing more than to be apart from one another. Developing a friendship toward Kayley, they join the party. Due to Kayley's insistence, Garrett misses a key warning from Ayden and is injured in an attack. During the escape, Kayley uses the forest's plants to heal Garrett's wounds, and they develop a mutual attraction and feelings towards one another.

Soon they come across the giant who is using the sword as a toothpick and manage to outwit Ruber again, trapping him and his minions with the giant as they slide uncontrollably down the mountainside. Garrett returns to the forest, having grown distant from the world of men and preferring to stay in the forest. Kayley starts toward Camelot, sword in hand, but is captured by Ruber and his thugs. Devon and Cornwall discover their power of flight, which only works when they cooperate or agree on something mutually. They rejoin Garrett, who mounts a rescue mission, but Ruber manages to gain entry to Camelot via disguise and traps himself with King Arthur with Excalibur; now grafted to his arm with his magic potion. Kayley is bound and gagged in the back of the cart, but is freed by Bladebeak who has a change of heart upon seeing Kayley's helplessness. Kayley and Garrett manage to fight their way with their friends' help to join with Arthur and in a fight, they manage to trick Ruber into inserting the sword back into the stone it had been pulled from. The magical forces conflict and completely disintegrates Ruber. The magic that spills on the kingdom separates all of Ruber's men (and Bladebeak) from their weapons and separates Devon and Cornwall, but the pair decide to reunite before the magic dissipates.

Soon after Kayley and Garrett are knighted as members of the round table, and they share a kiss. As the pair ride off into the sunset, their horse has a flag mounted to its back reading "Just Knighted".

• Jessalyn Gilsig (Andrea Corr, singing; Sarah Freeman, young; Athanassios Vakalis, animation) as Kayley, a farm girl with dreams of becoming a knight like her father. Kayley is based on the character Lynette from The King's Damosel, who was an expanded version of Lynette of Arthurian legend.
• Cary Elwes (Bryan White, singing; Chrystal Klabunde, animation) as Garrett, a blind hermit who once dreamed of becoming a knight. Garrett is a combination of two characters from The King's Damosel: The knight-in-disguise Gareth (from Arthurian legend) and the blind cave-dweller Lucius (an original character in the novel). Lynn Manning served as an advisor on blindness and martial arts.
• Gary Oldman (Alexander Williams, animation) as Ruber, an insane former knight who wishes to conquer Camelot. He is based on the Red Knight.
• Eric Idle and Don Rickles (Dan Wagner, animation) as Devon and Cornwall, a two-headed dragon. The two heads dislike each other and have difficulties flying and breathing fire (unlike most dragons).
• Jane Seymour (Céline Dion, singing; Cynthia Overman, animation) as Juliana, Kayley's mother and Sir Lionel's widow.
• Pierce Brosnan (Steve Perry, singing) as King Arthur, the king of legend.
• Bronson Pinchot (Stephen Franck, animation) as the Griffin, a griffin who is Ruber's main henchman.
• Jaleel White (Stephen Franck, animation) as Bladebeak; a chicken who is mystically merged with an axe.
• Gabriel Byrne as Sir Lionel, Kayley's knighted father; is killed by Ruber early in the movie.
• John Gielgud as Merlin, Arthur's legendary wizard friend and Ayden's master.
• Frank Welker (Mike Nguyen, animation) as Ayden, the silver-winged falcon owned by Merlin who aids Garrett.

1. "United We Stand" - King Arthur & Knights
2. "On My Father's Wings" - Kayley
3. "Ruber" - Ruber
4. "The Prayer" - Juliana
5. "I Stand Alone" - Garrett
6. "If I Didn't Have You" - Devon & Cornwall
7. "Looking Through Your Eyes" - Garrett & Kayley
8. "I Stand Alone (Reprise)"- Garrett

In May 1995, The Quest for the Grail was Warner Bros. Feature Animation's first announced project, and the studio put the film into production before the story was finalized. Animators spent considerable downtime waiting for management to make up their minds. Bill Kroyer (FernGully: The Last Rainforest) was originally going to direct with his wife, Sue, producing, but creative differences forced the husband and wife team to leave the project in February 1997.Kenny Ortega served as the film's choreographer. CGI was used for a few scenes, such as to create the rock ogre. According to Kit Percy, head of CGI effects, the software they used was designed for use with live-action.

Chrystal Klabunde, leading animator of Garrett, said in an article in Animation Magazine, "It was top heavy. All the executives were happily running around and playing executive, getting corner offices—but very few of them had any concept about animation at all, about doing an animated film. It never occurred to anybody at the top that they had to start from the bottom and build that up. The problems were really coming at the inexperience of everyone involved. Those were people from Disney that had the idea that you just said, 'Do it,' and it gets done. It never occurred to them that it got done because Disney had an infrastructure in place, working like clockwork. We didn't have that." Effects supervisor, Michel Gagné also said, "People were giving up. The head of layout was kicked out, the head of background, the executive producer, the producer, the director, the associate producer---all the heads rolled. It's kind of a hard environment to work in." Dalisa Cooper Cohen, producer of the film, said "We made this movie in a year, basically. That was a lot of the problem. We worked around the clock."

Reportedly, "cost overruns and production nightmares" led the studio to "reconsider their commitment to feature animation." Filmmaker Brad Bird (who helmed The Iron Giant, Warner Bros. next animated film) thought that micromanaging, which he said had worked well for Disney but not for Warner Bros., had been part of the problem.

The film was heavily promoted by Wendy's, who offered themed Kid's meals that included toys and discounts on theater admission. Warner Bros. also teamed up with UNICEF to promote the home video release of the film by advertising trick-or-treat donation boxes before Halloween arrived.

The film received mixed reviews from critics; it made $6,041,602 on its opening weekend and $22,717,758 during its theatrical run in North America, and the studio lost about $40 million on the film. The film was largely overshadowed by Deep Impact and the opening weekend debut of The Horse Whisperer, and the following week by the hyped release of Godzilla.

David Kronke of the Los Angeles Times wrote that the film is "a nearly perfect reflection of troubling trends in animated features," called Kayley "a standard-issue spunky female heroine," and said that "Garrett's blindness is the one adventurous element to the film, but even it seems calculated; his lack of sight is hardly debilitating, yet still provides kids a lesson in acceptance". Kevin J. Harty, editor of a collection of essays called Cinema Arthuriana, says that the film is “slightly indebted to, rather than, as Warner publicity claims, actually based on” Chapman’s novel.

The soundtrack was released May 5, 1998, ten days before the film's release. Although the film was not a critical or commercial success, the soundtrack did receive a certain level of praise. The album peaked at #117 on the Billboard 200, and won the Golden Globe Award for Best Original Song for "The Prayer", and was also nominated for the Academy Award for Best Original Song, also for "The Prayer" (though it lost the latter to "When You Believe" from DreamWorks' The Prince of Egypt).

The soundtrack is quite well known due to the celebrity vocals present on it, such as Celine Dion and Andrea Bocelli singing "The Prayer", LeAnn Rimes singing her single version of the movie's romantic duet, "Looking Through Your Eyes", The Corrs singing "On my Father's Wings", "Looking Through Your Eyes" and Steve Perry singing "I Stand Alone", which is also featured on his "Greatest Hits + 5 Unreleased" album. Gary Oldman is also on the soundtrack, singing Ruber's theme. "The Prayer" was nominated for an Academy Award for Best Original Song at the 71st Academy Awards and won the 1999 Golden Globe for Best Original Song - Motion Picture. One of the Celtic Woman members, Chloë Agnew covered "The Prayer" in full English. A former member of the same group, Deirdre Shannon, and her brother Matthew, one of The Celtic Tenors, covered it for her solo album. Another rendition of "The Prayer" was performed at the Closing Ceremonies of the 2002 Winter Olympics by Josh Groban and Charlotte Church.

Track listing

No.	Title	Artist	Length
1.	"Looking Through Your Eyes"	LeAnn Rimes	4:06
2.	"I Stand Alone"	Steve Perry	3:43
3.	"The Prayer"	Celine Dion	2:49
4.	"United We Stand"	Steve Perry	3:20
5.	"On My Father's Wings"	Andrea Corr	3:00
6.	"Looking Through Your Eyes"	The Corrs and Bryan White	3:36
7.	"Ruber"	Gary Oldman	3:56
8.	"I Stand Alone"	Bryan White	3:26
9.	"If I Didn't Have You"	Eric Idle and Don Rickles	2:55
10.	"Dragon Attack/Forbidden Forest"	Patrick Doyle	3:14
11.	"The Battle"	Patrick Doyle	2:49
12.	"Looking Through Your Eyes"	David Foster	3:57
13.	"The Prayer"	Andrea Bocelli	4:09

The video game was released in 1998 for Game Boy Color.

• List of films based on Arthurian legend