Five years ago, the notion of a movie about Legos seemed ridiculous, but after $500 million in box office receipts and two successful spin-offs, “The Lego Movie 2” is a highly- and understandably-anticipated event sequel. Phil Lord and Chris Miller, returning as co-screenwriters and producers, hand the reigns of this unlikely but irresistible franchise off to “Trolls” director Mike Mitchell for a story that builds (no pun intended) on the foundation of the first in terms of its thematic complexity, while expanding its eclectic landscape with the energy and abandon of an eight-year-old building a playset out of random bricks recovered from the forgotten corners of her toy box. Though not quite as effective as the first film (due in small part to a less clear idea, but also to the growing abundance of Lego-themed movies) “Lego Movie 2” exudes a certain sort of overpowering, sensory-overload charm to muscle its way into audiences’ hearts even if afterward their minds may remain a bit discombobulated by the experience.

Picking up right where the previous movie ended, Bricksburg has been overrun by destructive, childlike Duplo blocks, turning the city into a post-apocalyptic wasteland. Despite this, Emmet (Chris Pratt) retains his unrelentingly optimistic outlook on life, to the growing consternation of his jaded “special best friend” Lucy (Elizabeth Banks). But when General Mayhem (Stephanie Beatriz) attacks the newly branded “Apocalypseburg” and captures Lucy, Batman (Will Arnett) and all of Emmet’s closest friends, he embarks on a dangerous journey to the Systar System to rescue them from a matrimonial ceremony for Queen Watevra Wa-Nabi (Tiffany Haddish).

En route to Systar, Emmet encounters Rex Dangervest (also Pratt), a roguish, multitalented adventurer who agrees to help the wholesome hero save his friends. After hearing Rex’s sad story of abandonment and loneliness, Emmet soon finds himself conflicted about what to do -- especially after discovering that his friends have been seemingly brainwashed by Watevra. But as Rex teaches him some new skills -- not just to build Legos, but how to break them -- Emmet must decide whether to embrace his new mentor’s tough, unforgiving outlook on life as his likeliest means for survival agains an impending "Amompocalypse," or if he wants to stay the same the sweet, lovable construction worker who once believed that being special means staying true to yourself.

If the first “Lego Movie” was a thinly-veiled tribute to, and treatise on, creativity, “Lego Movie 2” feels in many ways like a manifestation of its inspirational message: screenwriters Phil Lord, Christopher Miller, Matthew Fogel and Raphael Bob-Waksberg tell a story that is literally born from the clashing imaginations of the two “real” children (played by Jason Sand and Brooklynn Prince) who have inherited their Dad’s (Will Ferrell) expansive toy collection. Unfortunately, that also means that its twists and turns, like those invented by kids with more enthusiasm than story sense, are often busy and sometimes overly convoluted, even if there are lots of fun diversions and digressions. At the same time, the film’s pop culture references -- from “Mad Max Fury Road” to “Aquaman” -- feel suitably organic for a pair of kids who undoubtedly have spent the intervening years between the first and second films consuming Hollywood’s biggest movies.

Some of the movie’s in-jokes work beautifully -- especially those involving Rex Dangervest, a possible alternate-dimension version of Emmet who is a composite of Pratt’s characters from “Guardians of the Galaxy,” “Jurassic World,” “The Magnificent Seven,” and the persistent rumors that he was slated to play Indiana Jones at one point. But in expanding the universe and yet holding onto the idea that what Emmett and his friends are doing springs from the minds of the human characters, “Lego 2” eventually makes some leaps into “Toy Story” realms of fanciful impossibility that kind of derail the overall premise of the franchise (or at least invite more scrutiny than it needs).

And yet, like Lord and Miller did with its predecessor, director Mitchell harnesses the limitless possibilities of a landscape that can be built, razed and rebuilt in the image of its creators for a dazzling visual and conceptual odyssey, though in this case to make an argument for cooperation, collaboration and mutual respect between disparate perspectives, both in the Lego and human worlds. Where the Lego characters continue to wrestle with their own identities, and with each other’s, the human kids do the same, trying to find an accord between an older brother’s evolving maturity, and a younger sister’s budding creativity. On screen, the end result is something discordant but joyful, unwieldy and frequently exhilarating, offering beautiful messages for kids about getting along with one another, and learning to respect different points of view. But ultimately, “The Lego Movie 2” feels like those lessons were imparted without quite being heeded by the filmmakers themselves, which may explain why the movie feels more like an exciting jumble of really intriguing parts than a unified, impactful whole.