The violent vigilante franchise returns as the charismatic actor tangles with the mob in Italy

Denzel Washington PHOTO: STEFANO MONTESI

When we first spot Denzel Washington’s Robert McCall in “The Equalizer 3,” a gangster is holding a gun very close to his head. Error. The malefactor is standing far too close, as McCall helpfully points out, and with just a nudge his pistol could be aimed at a fellow thug. Rarely unsporting, McCall gives these fellows, and a couple of other armed men in the room, nine seconds to make tactical readjustments. Nine seconds goes by rapidly when you’re in the presence of the Equalizer.

Watching Mr. Washington’s McCall bloodily delete bad guys remains a pleasure in the third installment of the big-screen series (inspired by the 1980s CBS television show, which was reworked for Queen Latifah in that network’s current version). Not only a superb actor, Mr. Washington is also one of the most charismatic movie stars of his generation, and like Tom Hanks he is almost guaranteed to defeat any attempt to dislike him.

McCall—a former intelligence officer and Marine with extraordinary sleuthing and assassination skills—was a sort of Home Depot Batman when we met him in 2014’s first movie in the series, in which he was a humble worker at a hardware superstore who launched a vigilante crusade against Russian mobsters to free an abused prostitute from bondage. As appealing as the actor is, he turns 70 next year, making him too old for action-hero feats. Plausibility is not a strong suit of this franchise, but it’s not supposed to be sheer fantasy either. It succeeds best when it makes McCall look ingeniously skilled rather than merely the beneficiary of impossibly good fortune.

The third installment, which like the first two is directed by Antoine Fuqua and written by Richard Wenk, is especially focused on slaughter, featuring a degree of gory violence that tips from the grotesque to the superfluous. If slaying is what you crave, “E3” has plenty. Yet the script is lazy throughout. Mr. Wenk has simply skipped the difficult parts—nailing down how McCall could overcome circles of snarling antagonists—especially in a climactic encounter in a house in which McCall’s go-to move is simply to keep popping up behind whoever is trying to kill him. Absent teleportation skills, this seems unlikely, and Mr. Wenk and Mr. Fuqua don’t bother outlining a path to how McCall executes such feats.

This time, McCall is in Sicily working his way through a Mafia-linked winery that is importing synthetic amphetamines from Syria, whose terrorists are in turn using the profits to fund attacks on civilians. Shot in the back, and bleeding unchecked for hours, he makes it back to the Italian mainland and is fortunate to be rescued in a Mafia-controlled town by a kindly cop (Eugenio Mastrandrea) and physician (Remo Girone) who, aware that the area is rife with evil men who richly deserve to be shot, nevertheless nurse him back to health with only one question asked: Is McCall a good man or a bad man? (He says he isn’t sure. He is praised for this answer.) The doctor notes that McCall was lucky: He was shot with only a .22-caliber rifle round. No biggie, apparently.

Dakota Fanning PHOTO: STEFANO MONTESI

While McCall recovers in a seaside town, he decides it feels like home (he speaks fluent Italian) but learns that everyone is cowering in fear of a sadistic pair of Mafiosi from nearby Naples, Vincent (Andrea Scarduzio) and Marco (Andrea Dodero), who are strong-arming locals into surrendering their property so they can develop it into resorts. Biding his time until he inevitably goes into weed-whacker mode against these creeps, McCall calls in a CIA desk analyst, Collins (Dakota Fanning, who last co-starred with Mr. Washington when she was in grade school, in 2004’s “Man on Fire”), to tip her off anonymously about the drug imports. Though she is such a low-level employee that she doesn’t even have a cubicle to herself, Collins sweeps in as a field agent to take a leading role in the drugs-and-terrorism investigation. Meanwhile McCall awaits his chance to equalize the gangsters, who twice have their guns trained on him but make the least of their opportunities. When he goes to work, so much red stuff gets splattered that it’s like a series of explosions at the marinara factory.

For those who can tolerate—or better yet, relish—extreme violence, “The Equalizer 3” is diverting enough. If the script is so-so, the beautiful Italian locations, Mr. Washington’s still-world-class charm and an eerie, frightening musical score by Marcelo Zarvos lift it (slightly) above average for the action-thriller genre. Mr. Washington won’t be getting an Oscar nomination for this one to follow the one he got for playing Macbeth, but the world needs airplane movies too. Slay on, McCall.