“Fast X” improves greatly when Momoa’s Dante Reyes begins his plan to torture Dom and his furious family. Roman (Tyrese Gibson), Tej (Ludacris), and Ramsey (Nathalie Emmanuel) head off to Rome on a mission, but it’s a trap designed by Reyes, the son of Hernan Reyes, who was killed when Dom and company rolled a safe through Rio in “Fast Five.” Dante says repeatedly that he doesn’t want to kill Dom; he wants him to suffer. That apparently entails an elaborate scheme to frame the gang as terrorists after a bomb explodes in the Italian capital. Following the construction of these films, at least since Vin and The Rock broke up, it’s just a way to divide the crew. Roman, Tej, Ramsey, and Han (Sung Kang) flee to London, where they run into Shaw (Jason Statham), of course. Letty (Michelle Rodriguez) ends up captured, and only Mr. Nobody’s daughter Tess (Brie Larson) and Cipher (Charlize Theron) can get her out. And that crowded synopsis doesn’t even include John Cena, Jordana Brewster, Daniela Melchior, Helen Mirren, Rita Moreno, or Alan Ritchson. It’s a crowded street race of a blockbuster.

And yet all of these famous faces are given so little to do. The Roman/Tej banter has never felt more tired; Moreno & Mirren each get one “supporting Dom” scene that sounds like A.I. wrote it; Cena gets trapped with Perry on an awkwardly conceived and executed road trip; only Theron and Rodriguez get to have any real fun in their subplot, fighting it out in one of the film’s best combat scenes. For the most part, “Fast X” is the Dom & Dante Show, and the film is at its most effective when it bounces Diesel & Momoa’s very different screen personas off each other. Diesel seems more stoic than ever while Momoa plays to the back row, going for flamboyant psychotic with every scene. He’s like a giant child in a superhero’s body, sticking out his tongue and gleefully hopping into chaos with a “Here we go!”

“Fast X” opens with a repurposing of one of the most famous scenes in the franchise from “Fast Five,” only inserting a de-aged Momoa into the action that fans remember. It’s almost as if that inciting idea became the creative force behind the entire film. Someone listed the best action scenes on a whiteboard and then asked how the energy of Momoa’s Dante could shift them. Sometimes it works. A drag race scene in Rio captures that more grounded energy from when the series was actually about people driving fast instead of defying physics. There’s a plane dropping a car again and harpoons with wires on the end. Even when the goofy action is working, it’s hard to shake the sense that all of “Fast X” is an echo of something you’ve seen before, and often done better with a director who understands stunt work and action geography better than the mediocre Leterrier. It doesn’t help that “Fast X” often looks poorly rendered in CGI terms, with actors more obviously against green-screen backgrounds than before. It reduces the stakes when we’re clearly watching something that’s more visual effects than stunt work.