PLENTY of movie franchises run into trouble on the second go-around, when a sequel tries to recapture the precise magic of an original and fails to find its own niche.

"The Lego Batman Movie," the first spin-off of the wildly successful and inventive surprise that was 2014's "The Lego Movie," is absolutely distinct from its predecessor.

In escaping the specific gravity of "The Lego Movie," though, it has wandered into the orbit of other Batman movies in ways that make it less radical, and less of a delight, than the movie that originated it.

One of the unique joys of "The Lego Movie" was the extent to which the movie genuinely felt like the creation of a child's mind.

It was a hodgepodge that repurposed everything from Krazy Glue, recast as a superweapon the characters refer to as "the Kragle," to the chewed-on stick from a Tootsie Roll pop that serves as the sorcerer Vitruvius' (Morgan Freeman) staff.

Writer-directors Phil Lord and Christopher Miller didn't bother to dress up their story with fancy titles; Vitruvius' prophecy refers to "the Special," who will defeat the fiendish "Lord Business" (Will Ferrell), who turns out to be a stand-in for the detached father to the very real little boy, Finn (Jadon Sand), who is telling himself the story that we are watching.

Magical kittens and Han Solo (Keith Ferguson) and Gandalf (Todd Hansen) and Batman (Will Arnett) all occupy the same fictional universe, their stories bleeding over into each other.

Wyldstyle (Elizabeth Banks), the heroine of the movie, makes her entrance in the film with the breathy line "Come with me if you want to not die."

"The Lego Movie" had ideas, too, namely about the way corporations profit by enforcing homogeneity and convincing consumers that they have genuinely distinct preferences rather than the tastes corporations have engineered for them.

Specifically, the Octan corporation produces everything in hero Emmet Brickowski's (Chris Pratt) world, including "music, dairy products, coffee, TV shows, surveillance systems, all history books, voting machines."

But even that idea has its catchiest expression in "Everything Is Awesome," a perfect earworm that sounds like what the result might be if a smart 10-year-old wrote the lyrics for a song with music by Max Martin.

"The Lego Batman Movie" by its very nature lacks that childlike looseness and improvisation. It's a highly referential parody, which means it requires the perspective that generally comes with being alive to watch pop culture evolve.

There are references to tropes in "The Lego Movie," like the head-spinning Good Cop / Bad Cop voiced by Liam Neeson, but they're asides rather than the loose, wide-ranging substance of the movie.

"The Lego Batman Movie" works best if you understand not merely how the depictions of Batman have evolved over the decades, but how those depictions, from Adam West's TV turn as "Batman" to Zack Snyder's much-derided "Batman v. Superman: Dawn of Justice," have been received.

The movie is absolutely arch and funny, but it lacks the anarchic goofiness that made "The Lego Movie" such a delight.

"The Lego Batman Movie," unlike "The Lego Movie," plays out in a hermetically sealed universe.

The third act of "The Lego Movie" reveals to us that Finn's father, known as the Man Upstairs, is the creator of Emmet's universe; he's a tie-wearing middle-aged man who has built a perfect, formulaic Lego metropolis in his basement and forbidden Finn and his sister to play with it, on pains of gluing the whole thing together so they can't change anything at all.

Emmet's adventures are the result of Finn's monkeying around with the Legos without his father's permission. The anti-corporate, pro-creativity message of the movie is as much a neglected son's bid for his father's affection as anything else, and lends a specific emotional weight to the ways in which Lord and Miller defied expectations for what a movie based on a toy could be.

For all "The Lego Batman Movie" comments on the tradition of which it is a part, specifically on the relationship between Batman and the Gotham police, it lacks a device that would allow it to reframe its own message in a similar way. And in fact, its message is essentially the same as every Batman story that preceded it.

Batman (Arnett again) becomes less isolated and solipsistic over the course of the movie. But by the end of the film, he's convinced new police commissioner Barbara Gordon (Rosario Dawson) not to worry about actually cleaning up crime in Gotham for good, the only thing that would truly end Batman's function in the city's civic ecosystem. It's ultimately conventional rather than radical.

"The Lego Movie" embraced the idea that you could tell any story with the same set of toys. "The Lego Batman Movie" ultimately suggests that you can tell only one.