Elsa, Anna and new power ballads

Sequels are tough! Especially with musicals.

The good-enough success of “Frozen 2,” then, deserves medium thanks and your allotted Disney money. The story pulls Elsa the Snow Queen and her less magical but nonetheless charismatic younger sister, Anna, into a murky web of Shakespearean political intrigue, with a large dose of Scandinavian pagan mythology. There are late-’80s/early-’90s-style power ballads from songwriters Kristen Anderson-Lopez and Robert Lopez, and just enough Olaf (snowman) and Sven (reindeer) to please younger viewers who, for years, after the first “Frozen” conquered the world in 2013, went to bed and then woke up singing “Let It Go.”

In one surefire comic interlude, at top speed Olaf recaps the narrative events of the first “Frozen.” And the lightning-quick “Let It Go” reference proves that the Lopez duo hasn’t lost its comic instinct.

That said, “Frozen 2” is more of a hairy quest deal, and knottier emotionally than the first. All’s well in the kingdom of Arendelle long enough for a generic happy-townsfolk number.

Then Elsa (voiced and belted by Idina Menzel) starts hearing a sirensong female vocalist emanating from somewhere up north, beckoning, waiting to reveal the truth behind her magical snow-sculpture powers, and the sisters’ parents’ death by shipwreck (another Shakespearean flourish).

With Anna (Kristen Bell), Anna’s amiable, supportive friend Kristoff (Jonathan Groff) and

Olaf (Josh Gad) in tow, Elsa discovers a mistshrouded land and a new set of human characters.

One of many intriguing notions in “Frozen 2” deals with the memory properties of water, so that water, in various forms, manifests a series of visual clues to the sisters’ fraught childhood. It’s like Emily in “Our Town,” revisiting her past, if Emily had ever learned to sing “Let It Go” in her more repressive era.

The moral is clear and repeated frequently: Always do “the next right thing.” That includes letting a couple of Disney princesses wear pants when they trek to lands unknown. The Lopez songs do the job without unearthing another enough-already earworm on the order of “Let It Go.”

But one of those is probably enough. Since Kristoff didn’t get to sing much in “Frozen,” the lovelorn lunk treats himself this time to a wry music video of his own, delivering power anthem “Lost in the Woods.” The movie itself occasionally gets lost in those woods, but finds its way back out again.

DISNEY VIA AP Elsa, voiced by Idina Menzel; Anna, voiced by Kristen Bell; Kristoff, voiced by Jonathan Groff; and Sven in a scene from “Frozen 2.”