“How to Train Your Dragon” may not be the most beloved of computer-animated franchises, but it is one of the most reliable. The latest installment, “How to Train Your Dragon: The Hidden World,” gives the now-trilogy a pleasing arc.

In the first movie (2010), Hiccup (voiced by Jay Baruchel), through a secret friendship with a not-so-fearsome dragon, Toothless, broke with centuries of Viking tradition to bring about a cease-fire (and cease-firebreathing) in human-dragon affairs. In “How to Train Your Dragon 2” (2014), Hiccup refined his leadership skills, ending the movie as a worthy successor to his father, Stoick (Gerard Butler), the chief of Berk, and his mother, Valka (Cate Blanchett), a pioneer in dragon whispering.

More bittersweet and less triumphal than its predecessors, and directed by a returning Dean DeBlois, “The Hidden World” concerns the exigencies that Hiccup faces as a leader, both politically and personally. If you truly love that dragon you trained, its message says, let him go.

As the movie opens, Berk is, in Hiccup’s estimation, “the world’s first dragon-Viking utopia.” But it’s not so utopian: Overcrowding is a problem at mealtimes, and the high concentration of rescued dragons in the settlement has made Berk a target for hunters. The most fearsome of those is a new villain, Grimmel (F. Murray Abraham, chewing on the cartoon scenery), who lives for the thrill of the chase and is always one step ahead of Berk’s peace-loving populace.

Should the residents hold strong, or must they abandon their centuries-old home? Is Berk just a state of mind? And is Hiccup finally ready for marriage with Astrid (America Ferrera)? Toothless, thought to be the last of his breed, meets a female counterpart and is quickly smitten. But is she on the level, or is Grimmel, who has Toothless in his sights, using her as bait?

Never the most sophisticated of digital dynasties, plot-wise, “How to Train Your Dragon” makes the most of these questions. If you’ve spent any time with these characters, it’s hard not to get swept up in the saga, and it’s easy to be moved by the bond between Hiccup and Toothless, who is, in effect, a very loyal dog who can fly and harness the power of lightning bolts.

The skill and detail with which the dragons have been rendered has only improved over the three films, and in sheer numbers, “The Hidden World” probably offers the most dragons per minute. The hidden world of the title — which Hiccup is searching for — is their secret ancestral homeland, depicted in glowing pastels that suggest a geological kinship with Pandora from “Avatar.”

But mostly the movie aspires to be goofy fun. Hiccup plays Cyrano during Toothless’ mating dance with his mysterious lady-dragon friend. Several former Judd Apatow associates (Jonah Hill, Kristen Wiig, Christopher Mintz-Plasse) are back as comic relief, although you suspect that some of them — along with Kit Harrington as a reformed dragon hunter and Butler — stopped by the recording studio only briefly. And unusually for a sequel, this installment has the courage to feel conclusive. The series has earned affection for its characters and its disarming premise. Now it’s time to let it go.

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‘How to Train Your Dragon: The Hidden World’

Rated PG for dragon courtship. Running time: 1 hour 44 minutes.

This article originally appeared in The New York Times.