NEW YORK OSV News – Chris Pratt reprises his starring role as Peter Quill, aka Star–Lord, in "Guardians of the Galaxy Vol. 3" (Disney), and writer–director James Gunn returns to helm the project. But there's a somber tone to long patches of this wrap–up of Gunn's trilogy, which also lacks the verve that characterized its predecessors.

As leader of the titular team of miscellaneous superheroes, Peter is naturally alarmed when a previously unknown enemy endowed with mighty fighting prowess suddenly invades the ensemble's headquarters, Knowhere. But anxiety turns to anguish when a confrontation with the new foe leaves his racoon comrade Rocket (voice of Bradley Cooper) gravely wounded.

To save Rocket's life, Peter and his fellow warriors – likable brawny dope Drax (Dave Bautista), shifty trickster–turned–straight arrow Nebula (Karen Gillan), tentacled Mantis (Pom Klementieff) and anthropomorphized tree Groot (voice of Vin Diesel) – embark on a quest. They're out to retrieve the computer code that will override Rocket's programmed resistance to medicine.

Along the path of their journey, they receive off–and–on aid from Peter's ex–girlfriend, Gamora (Zoe Saldaña). As fans of the interwoven "Avengers" franchise will know, Gamora was killed off, only to reappear as an alternate, younger version of herself. Not only does this mean she's gone from Guardian to brigand, it also means she doesn't remember Peter or their relationship.

As Peter grapples with this awkward complication in his once–flourishing romantic life, back at Knowhere, Rocket lies near death. While in a comatose state, he experiences a series of flashbacks to his youth.

These reveal that young Rocket was among the victims of a villain called The High Evolutionary (Chukwudi Iwuji) who used his hyper–intelligent prisoner as experimental fodder in a drive toward creating an ideal world populated by perfect beings. The torturous tinkering Rocket underwent included installing the technology that's currently keeping him from healing.

Along with its implicitly pro–life warning about the dangers of interfering with nature, Gunn's script satirizes the urge to resort to needless mayhem and highlights heroism and friendship. But the grim backstory to which much of the running time is devoted reinforces the movie's inappropriateness for kids.

Grown–ups, by contrast, will appreciate that the combat, although at times intense, is kept bloodless. They may also feel that even the weakest installment of a series rich in charm and wit is worth patronizing. If nothing else, they'll get one more chance to hum along with Redbone's 1970s hit, "Come and Get Your Love" – and who doesn't enjoy that?

The film contains much stylized but sometimes harsh violence, a torture theme, brief sexual humor, at least one mild oath, a single rough term and occasional crude and crass language. The OSV News classification is A–III –– adults. The Motion Picture Association rating is PG–13 – parents strongly cautioned. Some material may be inappropriate for children under 13.

John Mulderig is media reviewer for OSV News. Follow him on Twitter @JohnMulderig1.