When DreamWorks’ original “Trolls” movie was released, it wasn’t immediately apparent that the studio was launching a musical franchise. The rainbow-bright computer-animated feature boasted a sparkly soundtrack and the voice of Justin Timberlake as grumpy, gray-skinned Branch, but it wasn’t until the sequel — “Trolls World Tour,” released straight to streaming during the pandemic — that the series explicitly embraced its top-40 ’tude. Now, having survived the rock apocalypse of that film, the saga rewinds to explore Branch’s backstory … as the junior member of a boy band, BroZone, in zero-calorie sugar high “Trolls Band Together.”

If you’re wondering why this is the first you’re hearing that Branch once performed arena concerts — as the diaper-clad “Baby B” — with older brothers Floyd (Troye Sivan), Spruce (Daveed Diggs), Clay (Kid Cudi) and John Dory (Eric André), just imagine how his girlfriend, Queen Poppy (Anna Kendrick), must feel about the news. She’s a huge BroZone fan, rattling off a list of same-sounding song titles (Timberlake clearly has a sense of humor about his early-2000s musical and hair stylings). Plus, Poppy’s always wanted a sibling, telling Branch, “A brother is a friend who can never leave you,” when John Dory shows up years after the band broke up with a mission to rescue Floyd.

Floyd, “the sensitive one,” has been troll-napped by Velvet and Veneer (voiced by Amy Schumer and Andrew Rannells), a divalicious brother-sister singing duo from Mount Rageous who’ve figured out a way to extract trolls’ musical talent in order to boost their own. These two are tall, bendy white characters with stringy green hair and googly Pac-Man eyes (the way Max Fleischer used to draw them, with a wedge missing), who want be famous, but can’t be bothered to work for it. It’s not clear how they trapped Floyd in the first place, but now they’ve drained him of nearly all his lifeforce and are plotting to lure the other BroZone members into a trap.

That’s all you need to know about the plot, beyond the joke that Floyd’s trapped in a diamond prison, and the band members believe that if they can hit the perfect family harmony, their voices can shatter diamonds. “We’re out of sync,” Floyd tells Branch. “We’ve gone from boys to men, and now there’s only one direction for us to go: the backstreets.” With gags like that, it’s not clear if this film is a boy-band parody or a feature-length advertisement for same. The answer, of course, is both, and judging by the tweens dancing in and out of their seats at the film’s Animation Is Film Festival premiere, the target audience doesn’t need an ironic wink to justify the guilt-free pleasure of an NSYNC reunion.

As with Illumination’s “Sing” sequel, the series has gone from being a music-driven kiddie confidence booster to a sales pitch for the ultra-processed mainstream music industry. Here, the soundtrack consists of mash-up “oldie” medleys, including a high-energy sequence that connects the Jackson 5’s “Candy Girl” with “You Got It (The Right Stuff)” by New Kids on the Block (both songs by sibling-bond bands). The vocals have all been Auto-Tuned to extreme, but at least we’re not dealing with those Alvin and the Chipmunks’ irritating falsettos.

Not all studio toons need to take themselves seriously. So what if Elizabeth Tippet’s script is made up entirely of one-liners and aphorisms? Directed by Walt Dohrn (who’s been with the franchise since the beginning), “Trolls Band Together” embraces its own silliness, featuring trippy sequences that switch over to ’70s-style hand-drawn animation. (Like a cross between underground comics and “Midnight Gospel,” the Rhonda “Hustle” sequence is surreal in all the right ways.) The movie’s conceived as a feature-length party, featuring a Bergen wedding, an island resort vacation, an amusement park chase and several concerts — which is a lot more fun than the dark and downbeat “Trolls World Tour.”

From the franchise’s first entry, the arts-and-craftsy design has been a selling point, with flocked skin textures and felt-like production design. That’s still the case here, as the team finds creative uses for pool noodles and water beads that give everything a tactile workshop feel, as if the whole movie had been put together in an Etsy seller’s workshop. Even the villains are cute, as is their overworked assistant Crimp (Zosia Mamet). In a world where Taylor Swift’s “Eras Tour” is drastically outperforming the likes of Martin Scorsese movies, haters are trolls, and trolls are just what the audience ordered.