You thought it was tricky to train a dragon?

It’s even trickier to take a much-admired animated film and make a sequel that feels satisfying and worthwhile. And it’s harder still to balance the competing needs of stretching the story in new directions but retaining the guiding spirit of the original enough to make fans happy.

It’s nice to be able to report that “How to Train Your Dragon 2,” written and directed by Dean DeBlois, does all that tricky stuff pretty darned well. And you’ll be happily surprised at the new twists it takes ― sort of like getting an unexpected second candy bar in the vending machine. “How to Train Your Dragon 2” doesn’t play it safe, and that’s why it’s the rare sequel that doesn’t feel somewhat stale.

The story returns us to Berk, where our young Viking hero, Hiccup (again voiced by Jay Baruchel), lives and frolics with his devoted dragon, Toothless, whom he befriended in the first movie, with momentous ramifications for human-dragon relations. Five years have passed, and now Berk is a virtual playground for dragons and Vikings alike. 

An amusing opening sequence shows the new pursuit of dragon-racing, a game that vaguely resembles Quidditch. And adjustments have been made to enhance dragon-human coexistence: for example, an aqueduct system, to quickly put out those pesky dragon-breath fires.

Hiccup, though, isn’t into the games ― he’s attracted to the beautiful skies, and spends his time exploring them, aboard Toothless, adding to the map he’s making of the world. His first scene of airborne frolic with Toothless is absolutely beautiful, and a sign of the visual delights to come.

Hiccup’s restless nature, though, is at odds with the aspirations of his burly father, Stoick the Vast (a sweetly gruff Gerard Butler), who wants Hiccup to take up new responsibilities. But Hiccup doesn’t feel leadership is really his thing. That’s what he tells spunky Astrid (America Ferrera, back from the first film), who is now his girlfriend, as well as a fellow explorer. (Other famous returning voices are Jonah Hill as Snotlout and Kristen Wiig as Ruffnut.)

One day Hiccup and Astrid make an ominous discovery: A trapper’s fort. Eret, son of Eret (Kit Harington) is cocky and ambitious. But his boss? He’s evil. That would be Drago Bludvist (Djimon Hounsou), a vicious villain who’s building a dragon army. Hiccup resolves to stop him.

And someone else, he learns ― a mysterious figure in the skies ― is also fighting Drago. Her name is Valka, and she is, shockingly, none other than Hiccup’s mother, long presumed dead. In fact, Valka ― voiced by Cate Blanchett in an elegant, otherworldly accent ― has spent these long years saving dragons. The scene in which she shows him the fantastic oasis where these rescued dragons live ― a tropical wonderland inside a giant ice formation ― is a marvel of color and inventive design, probably the prettiest scene in the film.

For a while, it seems like a perfect family reunion. But happiness is short-lived. Valka doesn’t believe, as her family does, that dragons can live with humans ― humans can be too cruel. And Drago, with his violent plans, is proving her right.

Without giving away too much, this is where the film travels into darker areas than its predecessor, displaying an admirable maturity. (AP)