Like the first installment, “How to Train Your Dragon 2” is essentially a boy-and-his-dog (or if you prefer, boy –and-his-horse) movie, except that the kid is a Viking and his pet a lovable—well, dragon. But it adds a third element to the mix—a villainous fellow named Drago Bludvist, who trains dragons to be destructive slaves rather than loyal and loving companions. The title might have been changed to “How and How Not to Train Your Dragon,” and the message is clear: when animals go bad, it’s the fault of their humans. (For an even more blatant example of that sentiment, see Sam Fuller’s still-controversial 1982 “White Dog.”)

In this case, though, audiences will probably be more interested in the colorful excitement of the tale Dean DeBlois has constructed than the moral he’s imparting. DeBlois has taken over full writing and directing duties this time around, and sets the action five years after the 2010 original (which was, of course, followed by a popular cable TV series). The realm of Berk is still ruled by the formidable Stoick (voiced by Gerard Butler), but it’s now an idyllic place where humans and dragons live in jovial harmony and youngsters like Astrid (America Ferrera), Fishlegs (Christopher Mintz-Plasse), Snotlout (Jonah Hill), Tuffnutt (T.J. Miller) and Ruffnut (Kristen Wiig) ride their flying critters in a sport that involves sheep that are hurled into the air via catapult, to be snapped up by the players and deposited in waiting baskets.

Missing from the contest is Stoick’s son—and Astrid’s boyfriend—Hiccup (querulous-sounding Jay Baruchel), the juvenile hero of the first movie, who now spends his time investigating new lands on his dragon Toothless and mapping them out. It’s on one of those trips that he and Astrid encounter a group of trappers led by Eret (Kit Harington) and engaged in capturing dragons for their master Drago (Djimon Hounsou), who’s intending to use his army to conquer the world. After returning to Berk to inform his father of the coming danger, Hiccup ventures out again to try to reason with Drago. But his journey instead takes him to what amounts to a dragon preserve, created by an alpha dragon called the Bewilderbeast and protected by a mysterious masked figure revealed as Valka (Cate Blanchett). She turns out to have a prior connection with both Hiccup and Stoick (the mythology of “Star Wars” is at work here), who shows up with his loyal sidekick Gobber (Craig Ferguson) not long before Drago arrives with an alpha dragon of his own. It’s alpha versus alpha to determine the fate not only of the sanctuary but of Berk as well.

“Dragon 2” is told on a larger canvas than the first film, but the realization is equally impressive. The visuals are similarly remarkable, with the production design of Pierre-Olivier Vincent and the art direction of Zhaoping Wei matching those of “Dragon 1” and the input of ace live-action cinematographer Roger Deakins once again an invaluable resource. Both the vast, lustrous backgrounds overseen by layout head Gil Zimmerman and the characters—both human and dragon—designed by Nico Marlet and animated by the crew under Simon Otto come across beautifully in images that are enhanced by 3D effects that are for the most part subtly employed. Complementing them are flavorful voice work and John Powell’s score, alternately lush and propulsive, which makes room for a musical interlude that eschews pizzazz in favor of a gentle, lilting Celtic ballad.

It could be argued that “How to Train Your Dragon 2” is too much of a good thing, stuffed to the brim with high-flying aerials, extended battle sequences (including one between the two alphas that can only be compared to rhinos or elephants butting heads, as well as a culminating face-off in defense of Berk that serves up climax after climax), and messages about self-sacrifice for the greater good and learning to accept the responsibility that comes with growing up. Some of the material, moreover, might be too dark and forbidding for small children, whose ability to sit still could also be taxed by the 100-plus-minute running-time.

But it will be hard for anyone to resist the antics of Toothless, who’s often shown playfully frolicking with other dragons in the background as the humans talk up front, and whose last-act transformations bring both loss and eventual triumph. Though voiceless, the beast is an expressive as most of the human characters, and more endearing than many of them. His fellow critters don’t have an awful lot of personality, but he boasts a good deal of it, and it’s the bond between him and Hiccup that encapsulates DeBlois’ major theme about how man’s treatment of animals determines how they will act. (Of course, whether it oversimplifies the natural order of things is another matter. Children also need to learn that wild creatures can’t always be tamed—and shouldn’t be expected to act in a benign fashion.)

But while “Dragon 2” is a rather different critter from “Dragon 1”—bigger, more sprawling and preachier—it has no less heart and humor, and is a rousing adventure besides. It’s no wonder a third installment is already in the works.