Grade: A-

An animated film about a magical world that casts an enchanted spell of its own, Thom Moore’s wondrous follow-up to “The Secret of Kells” also acts as a lovely 2D, traditionally drawn rejoinder to the recent trend toward 3D, computer-generated animated children’s movies. (Actually, there are 3D glasses here, but only ones that are occasionally donned by the young boy at the center of the plot as part of his superhero costume, which also includes a cape.) Filled with beautiful images but also with content that doesn’t insult a viewer’s intelligence, “Song of the Sea” deservedly copped an Oscar nomination, and though it probably won’t win, it should.

The script, written by Will Collins from a story by Moore, deals with the same sort of subjects that many Hollywood family films do—the grief that comes from the loss of a parent and the need to restore the family dynamic. But it does so through the lens of Celtic myth. Young Ben (David Rawle), the ten-year old son of lighthouse keeper Conor (Brendan Gleeson), blames his still-speechless sister Saoirse for the death of his mother Bronagh (Lisa Hannigan) six years earlier. She disappeared into the ocean just as she was giving birth to the girl, whom Conor rescued on the shore. Ben chafes at caring for Saoirse, refusing to let her play with the conch his mother had given him and often telling her frightening stories of the great fairy king Mac Lir (also voiced by Gleeson), who was turned to stone by his mother, the witch Macha, in order to free him of the sadness brought by losing his daughter.

When Conor’s mother (Fionnula Flanagan) visits for Saoirse’s birthday and the girl almost drowns as the result of her nocturnal wandering, the old woman demands that she take the children to live with her in the city. Conor agrees, but Ben is determined to return home, especially since his dog Cu was left behind. Saoirse insists on accompanying him, but it’s not long before she’s abducted by three fairies that are among the few of their kind whom Macha (also voiced by Flanagan) hasn’t turned to stone by extracting their emotions from them. They recognize the girl as a selkie, a creature that lives as a seal in the sea but is transformed into a human on land—and not just a selkie, but a special one, born of her selkie mother by a human father, who can liberate the magical realm from Macha’s spell by singing her song while wearing the translucent coat her mother had swaddled her in as an infant.

Ben must now heed his mother’s injunction to become the best of big brothers by getting Saoirse back to the lighthouse with the magic conch left by his mother and retrieve the coat they left behind so that his sister can fulfill her destiny. The mission takes the children into encounters with other mythic folk and eventually to the keep of Macha, who threatens the girl’s spirit; to save her, Ben will have to overcome his fear of water and a host of other dangers, but success will free the world of magic from stony paralysis and even allow a reunion with Bronagh.

“Song of the Sea” shares many of its beats with other animated films, but it invests them with emotional richness and moments of charming humor. (Nor is it the first film to use the selkie mythology to advantage. Both John Sayles’ “The Secret of Roan Inish” and Neil Jordan’s “Ondine” did so as well.) The voice work is delicious, with Rawle contributing an especially likable performance as Ben and both Gleeson and Flanagan filling their multiple roles with relish. The supporting cast is all excellent as well.

But what truly sets the film apart is the array of astonishing images that Moore and the large crew of craftsman associated with his Kilkenny-based Cartoon Saloon have to offer. The character animation doesn’t strive for realism, opting instead to portray the children and grownups in a flat style that borrows from Japanese models as well as imaginative television toons. And the backgrounds, as realized by production designer Adrien Mergeau, use watercolors to set off the characters, as well as splashes of magical lights that dance across the screen. A culminating sequence involving a journey beneath the sea offers further opportunity for the artists’ inventiveness. And everything is accompanied by a lovely Celtic music score from Bruno Coulais and the Irish band Kila, which includes songs featuring Gaelic lyrics and instruments.

“Song of the Sea” isn’t a children’s film, though they might be enchanted by it. Rather it’s a film that will appeal to adults just as much, and perhaps more. It’s testimony not only to the exquisite craft possible in the medium of 2D animation, but to how beautiful animated features can be in terms of narrative as well as imagery. It puts most studio efforts to shame.