It’s silly to say that actors are the characters they play, but it’s naïve to say that they totally aren’t. That’s what has caused such a problem for Mel Gibson. He’s not the first celebrity to be sunk by bad behavior, but the lingering scandal is that it’s not just the things he said; it’s that everyone heard him on those leaked recordings — heard him screaming and roaring, heard his boiling rants of hatred. How can he go back to playing a movie star we like, pretending that he’s not…that guy? (Who’d believe it?) The answer is: He can do it, just maybe, by playing a movie star who is that guy.

That, more or less, is what he does in “Blood Father.” Directed by Jean-François Richet, who made the lumpy two-part “Mesrine” gangster saga, the picture is an obvious stab at career rehabilitation in the form of a scuzzy-bloody B-movie rescue-and-revenge thriller. It’s grimy sadistic action pulp, way down on the totem pole of respectability. If you compare it to, say, the revenge thrillers that Liam Neeson made to reboot his career, starting with “Taken” (2008), the difference is that the Neeson pictures, lurid and badly plotted as they often were, had a certain high studio gloss, whereas “Blood Father” is as basic as a ’70s grindhouse film. It’s 90 hardened minutes of shotgun mayhem, drug goons with tattoos up to their throats, and a general dirty meanness that extends to everyone on screen. But that makes it a perfect platform to launch the comeback of Mel Gibson: an actor who’s been shoved off the radar more ignominiously than any Hollywood star since back in the day when Mickey Rourke was doing movies like “Harley Davidson and the Marlboro Man.”

“Blood Father” builds on Gibson’s downfall, in part by structuring itself as his penance. We first confront the actor in extreme close-up, and his appearance is a shock: his face more creased than we’ve ever seen it, much of it hidden under an ugly beard with a thatch of gray that just about screams “prison hair.” Within seconds, it’s clear that our hero is delivering an AA testimonial, and it’s a tersely brutal one, an acerbic story about how he lost everything — which, of course, the film presents as an analogue of Gibson’s own predicament. His character, Link, is an ex-con who lives in a sucky wilderness trailer park on the outskirts of L.A., where he inks tattoos for a living right out of his trailer and hangs with no one but Kirby (William H. Macy), his sponsor and fellow deadbeat.

It’s a stable non-existence, but it needs shaking up. And who better to do that than Lydia (Erin Moriarty), Link’s estranged teenage daughter, who vanished a year ago from her mother’s home? She has fallen in with Jonah (Diego Luna), a seething outcast from the Mexican drug cartels (not good people to be outcast from), and he, in turn, has tried to make her his gangster moll, which results in a shootout gone wrong — the film’s in media res opening sequence — that ends with Lydia on the run, desperate for cash and a safe harbor. So she calls up her dark-side daddy.

In Jodie Foster’s “The Beaver” (2011), which was Gibson’s first — failed — attempt at acting rehab after his flameout, he played a depressed CEO and family man who had a breakdown and decided that he would now communicate only by using a goofy beaver hand puppet. Leaving aside that this was a less than transcendent idea for a movie (whoever was going to star in it), Gibson was the wrong actor at the wrong time. His onscreen breakdown was supposed to be a cheeky acknowledgment of his private woes, but it was too wacky and harmless. “Blood Father,” on the other hand, lets Gibson act like a wasted badass, putting him in a kind of hell-hole comfort zone, so that he seems both more at home and more honest. Not to mention: He’s damn good at playing a bulgy-eyed reckless jerk! Who’s been chastened by life…but not much!

On the run with his daughter, in a slope-backed car that looks like it came out of “Vanishing Point,” Gibson shows off his gift for tossing out fast and furious quips. At the same time, we need to believe that he cares about Lydia (there’s a huge tattoo of her face on Link’s forearm), and Gibson and Moriarty develop a nice, unforced snarky interplay. The plot is utterly predictable: lots of driving, some of it on choppers shot with a touch of Mad Max nihilism, all leading up to the surprise return of a character we knew in our guts wasn’t dead. There’s one moment when the movie turns nimble: The cult singer and actor Michael Parks shows up as Preacher, an old pal of Link’s who is hawking white-supremacist merchandise, and Parks takes this barely written scoundrel and turns him into a wily person of interest.

“Blood Father” is trash, but it does capture what an accomplished and winning actor Mel Gibson can be. Just because he lost his bearings, and his career, doesn’t mean that he lost his talent. Going forward, if all he gets to do is angry-crazy Mel Gibson shtick in boilerplate thrillers like this one, it would be a shame. “Blood Father” looks like a throwaway, and it is, but the best way to think of it might be as an audition: a way to remind people that Gibson, if given the chance, could juice up a serious movie. At some point, he deserves to be let out of the Hollywood doghouse.