Dwayne Johnson’s new film “Fast & Furious Presents: Hobbs & Shaw” is not as solid as a rock. Balsa wood, maybe, or a bar of soap.

The flick’s flimsiness is not the Rock’s fault. If you had told me in 2002 that the former wrestler would end up being one of the only bankable movie stars left in Hollywood, I would have said, “Go home, you’re drunk.” But it’s true, and he’s rightly earned that status. The Rock is funny and charismatic in “Hobbs & Shaw,” and his bro chemistry with co-star Jason Statham is a joy. The pair slinging vicious insults at each other is almost vaudevillian — it would make a decent live tour.

And then there’s the rest of the movie.

The first spinoff in the “Fast & Furious” franchise has misguidedly been made into a ho-hum spy comedy.

Luke Hobbs (Johnson), an American federal agent, and Deckard Shaw (Statham), a British mercenary, are brought together to find the villain who stole the Vitamix of viruses, an infection that quickly liquefies a person’s internal organs. Complicating matters, the person who actually holds the virus is Hattie (Vanessa Kirby), Deckard’s sister, who’s also an agent. Hobbs and Shaw need to save her, destroy the substance and bring down a bloke named Brixton (Idris Elba).

He’s the bad guy. How do we know? When Brixton, a genetically engineered human who wears a technological suit straight out of “Black Panther,” first enters, somebody asks him, “Who the hell are you?”

“Bad guy,” he says. Thanks for the help!

Later, when Brixton is told, “You can’t save the world with genocide!,” he goes, “Genocide, schmenocide!”

Genocide, schmenocide? Most of the humor outside of Johnson and Statham trading barbs is similarly lazy, like its star cameos: Helen Mirren doing a lousy cockney accent as Shaw’s incarcerated mum; and Ryan Reynolds with his usual Paul Rudd-on-crack line delivery. The best appearance is Kevin Hart as an air marshal who wants to see some real action.

The editing is often as slack as the jokes. The final fight sequence, set in Samoa, takes place over a 30-minute countdown to disaster for the characters. In that time, the sky goes from total darkness, to midday sunny, to cloudy and then back to blue skies again. I know it’s an island, but sheesh.

There are two big chases, which live up to the series’ entire reason for existing. One travels through major London arteries and features a “Transformers”-esque motorcycle that can squeeze into impossibly small spaces.

The other is set outside a secret lair in Ukraine. Why, you think, can’t the filmmakers extend the cleverness and innovation of their automotive pursuits to, say, plot and dialogue?