[4][5] It was directed by Tomm Moore and Nora Twomey, produced by Paul Young, Didier Brunner and Viviane Vanfleteren, written by Fabrice Ziolkowski, distributed by Gébéka Films in France, Kinepolis Film Distribution in Belgium and Buena Vista International in Ireland, edited by Fabienne Alvarez-Giro and music composed by Bruno Coulais and Kíla.

Aidan arrives in Kells, accompanied by his white cat with heterochromatic eyes, Pangur Bán,[7] after escaping from his monastery at Iona in a small boat as it is destroyed by a Viking raid (seen in brief in the opening titles).

Seeing Brendan as a suitable apprentice, Aidan sends him to follow Pangur Bán out of a secret passage under the abbey wall which the cat has found, out into the summer woods to obtain gall nuts to make more ink.

Declaring that the book will never be completed without the Eye, Brendan persuades Aisling to help him enter Crom's cave, narrowly escaping death in the process.

The wooden staircase to Kells' central tower becomes overloaded with panicked villagers and collapses, while the encampment and the other abbey buildings around it are set ablaze.

Unable to help the Abbot or any of the others, Brendan and Aidan flee to the forest with Pangur Bán and their illuminated manuscript via the cat's secret passage, as the Vikings breach the main chapel and attack the monks and villagers hiding within.

It also draws upon Celtic mythology;[8] examples include its inclusion of Crom Cruach, a pre-Christian Irish deity[9] and the reference to the poetic genre of Aislings, in which a poet is confronted by a dream or vision of a seeress, in the naming of the forest sprite encountered by Brendan.

Wider mythological similarities have also been commented upon, such as parallels between Brendan's metaphysical battle with Crom Cruach and Beowulf's underwater encounter with Grendel's mother.

[10] The Secret of Kells began development in 1999, when Tomm Moore and several of his friends were inspired by Richard Williams's The Thief and the Cobbler, Disney's Mulan, Gustav Klimt's paintings, John Bauer's illustrations and the works of Hayao Miyazaki, which based their visual style on the respective traditional art of the cultures featured in each film.

[13] Rotten Tomatoes critics concluded that the film was "Beautifully drawn and refreshingly calm, The Secret of Kells hearkens back to animation's golden age with an enchanting tale inspired by Irish mythology.

Joe Morgenstern of The Wall Street Journal said that "it pays homage to Celtic culture and design, together with techniques and motifs that evoke Matisse, Miyazaki and the minimalist cartoons of UPA".

[15] Gary Thompson of the Philadelphia Daily News said The Secret of Kells "is noteworthy for its unique, ornate design, its moments of silence... and gorgeous music".