“How to Train Your Dragon: The Hidden World” marks the franchise’s final chapter. And it’s one that will speak to parents and kids alike.

The How to Train Your Dragon trilogy is one for the ages and truly mythic. Introduced in 2010, the series’ protagonist, Hiccup (voiced by Jay Baruchel), was a typical would-be comic figure. A young Viking from a clan of dragon hunters, he encounters his match among the dragons — whom he dubs Toothless — and the pair shift the known paradigm. They prove that Vikings and dragons can work together and move forward into a brave new future. But to do so, Hiccup must convince his warrior father, the clan leader Stoick (ruggedly voiced by Gerard Butler) to go against every instinct of their people.

In the second installment, we see Hiccup and Toothless stumble upon a cave full of wild dragons and an enigmatic Dragon Rider, who turns out to be his mother Valka (Cate Blanchett). They must broker a new peace between Viking dragon riders and the growing wild population of dragons, who remain the target of hunters.

For all the humor and spirited flights of fancy captured in this fantastic world, writer-director Dean DeBlois — working from the How to Train Your Dragon book series by Cressida Cowell — doesn’t shy away from the conflicts and tragedy needed to define the journeys of his evolving protagonists.

The Hidden World is the final chapter in the epic ride of Hiccup and Toothless. Up to this point, it had been assumed that Toothless, a Night Fury (and alpha among the dragons), was the last of his kind. But the arrival of a female Light Fury with special abilities beyond anything Toothless had previously displayed sparks renewed threats from human dragon hunters, especially a brutal mercenary named Grimmel (F. Murray Abraham) intent on wiping dragons out once and for all.

Seeking again to protect the dragons and his dragon-loving people, Hiccup latches onto lore that details a lost utopian realm beyond the end of the Earth, where he believes his people (and their dragons) can be free. As chief of the clan, it falls on him to push past his doubts and fears to lead everyone toward this new homeland. For all the focus on Hiccup and Toothless, it would be unwise to forget that Hiccup has a whole community of Viking peers — from the brave and loyal Astrid (America Ferrera) to the comic bumblers Snotlout (Jonah Hill), Fishlegs (Christopher Mintz-Plasse) and Ruffnut (Kristen Wiig) — who have his back. We’ve watched this gang of misfits grow into a stalwart and loveable collection of heroes, who are capable of challenging and redefining cultural and social norms.

Lessons of acceptance abound throughout the How to Train Your Dragon franchise. It has been devoted to presenting communities (both human and dragon) teeming with characters who have disabilities and physical limitations who develop adaptations that lead to more accessible spaces.

Despite the assembled talent, the narrative and the characters themselves steal the show. We care about Hiccup, his friends and this world, which runs counter to our expectations about the lives of Vikings and dragons. There’s a sneaky curriculum complete with social and cultural justice points that never becomes didactic or heavy-handed. Kids get to enjoy the humor and whiz-bang visual style, but The Hidden Worldwill speak to parents. It reminds us of our own early days, the fun of spending time with friends, realizing how much our own parents meant to us, and how we pass that love and sense of responsibility along to the next generation.

Several strong animated franchises — Toy Story and The LEGO Movie, to name two — have crafted moving portraits of idealized childhood relationships and the power of imagination. But with The Hidden World, How to Train Your Dragon turns the neat trick of telling a story for adults in a way that kids can enjoy too. That is what a coming-of-age story looks like. (In theaters) Grade: A