From left, Pom Klementieff as Mantis, Groot (voiced by Vin Diesel), Chris Pratt as Peter Quill/Star-Lord, Dave Bautista as Drax, Karen Gillan as Nebula in a scene from “Guardians of the Galaxy Vol. 3.” Marvel-Disney via AP

There’s a world of contradiction wrapped up in “Guardians of the Galaxy Vol. 3.” On the one hand, like almost anything to come out of Marvel these days, it’s long and loud – both qualities due as much to the noisy, protracted battle sequences as to the (over)use of retro needle drops that accompany them, courtesy of superhero Peter Quill’s signature playlists, which here include the Beastie Boys’ rap-rock anthem “No Sleep Till Brooklyn” – its opening guitar chords cued up on Peter’s music player as he and the Guardians stride forward in slow motion to engage the enemy du jour. On the other hand, the new movie centers on something small and quiet: the backstory of Rocket Raccoon.

It’s a sweet and savory morsel of storytelling, drowning in a puddle of special-effects sauce.

That the character Rocket, so poignant and affecting in this origin tale, is a CGI creation voiced by Bradley Cooper only adds to the irony. Although the film opens with Peter, also known as Star-Lord (Chris Pratt), drowning his sorrows in booze over the death in “Avengers: Infinity War” of his green-skinned girlfriend, Gamora (Zoe Saldana), “Vol. 3” is wholly Rocket’s story. Don’t take my word for it: As Rocket’s soul mate, a talking cyborg otter named Lylla (voice of Linda Cardellini), tells him toward the end of the film, “The story has been yours all along. You just didn’t know it.”

Did I say the death of Gamora? As fans noticed in the trailer, she’s back – an anomaly the film lightly dispenses with by characterizing her presence as an “alternative future version” of the character who has somehow been restored by time-traveling back to the past in a separate storyline of the Marvel Cinematic Universe. Don’t sweat it. As Peter himself notes, it’s complicated: “I’m not some freakin’ Infinity Stone scientist.” This version of Gamora is not interested in Peter. Not at first, anyway.

There are other new characters introduced, including a telekinetic golden retriever mix in an astronaut suit called Cosmo the Spacedog (Maria Bakalova) and Adam Warlock (Will Poulter), whose violent appearance in the film’s opening minutes leaves the half-cybernetic, half-trash-panda Rocket badly injured, setting in motion the main plot, which is to retrieve a computer passkey that will override the kill switch that has been programmed into Rocket’s circuitry by his creator.

That is the film’s main villain, a man known as the High Evolutionary (Chukwudi Iwuji). He’s a mad scientist whose dream is to create something called Counter-Earth: a sort of global version of “The Island of Dr. Moreau,” featuring mutant talking animal-people. Yes, it’s all very silly. There may be another reason they call this guy the High Evolutionary. His vision is literally trippy. The film jumps around from the headquarters of the High Evolutionary’s Orgocorp – a villain’s lair that looks like a futuristic food court built inside a giant “bioformed” stomach – to various other settings that appear to have been dreamed up by a production designer in an altered state.

“Let’s get that passkey and save our friend!” Peter keeps shouting, as if one needed reminding. (One may, given that the quest goes on so long – and on so many different fronts – that it’s sometimes hard to keep track of where scenes are taking place and why. “Vol. 3” is the most confusing and least fun of the series, which had been notable for its lightness and sense of self-aware humor.)

Rocket, voiced by Bradley Cooper, in a scene from “Guardians of the Galaxy Vol. 3.” Marvel-Disney via AP

Told in flashbacks sprinkled throughout the film, the story of Rocket’s past, which had been hinted about in the previous films, gives viewers something – and someone – to actually care about. Never mind that it’s not a person. Coupled with Cooper’s sensitive vocal performance, the creature animation has an emotional richness, giving Rocket’s journey a powerful resonance. It feels weird saying this, but the raccoon’s tale is the only moving part of this movie.

That’s just one paradox of many. “Guardians of the Galaxy Vol. 3” is said to be the last film of a trilogy, and there is the bittersweet air of a leave-taking, a farewell, in the closing credits, which run over an assortment of snapshots from the other two films. And yet my heart sank a little – hardly the reaction Marvel wants – when I read these words as the last credits rolled: Star-Lord will return.