Denzel Washington kills in “The Equalizer 2”

★★★5 Rated R. 120 minutes.

You won’t usually find Denzel Washington in a movie sequel. He just doesn’t do them. Something about not wanting to repeat himself. So there must be something special indeed for him to break his own rule for “The Equalizer 2.”

Fans of the first film will instantly know why Washington is drawn to the character of Robert McCall, a quiet middle-aged retired special-ops agent who fiercely believes in justice, likes to help others and dispenses the occasional lethal killing for those deserving.

“We all have to pay for our sins,” he tells a group of very bad guys in the new, highly satisfying edition, before vowing to hunt each one dead. His only regret? He can kill them only once.

“The Equalizer 2 “reconnects many of the people behind the 2014 debut alongside the always-vital Washington — Antoine Fuqua returns to direct, as does writer Richard Wenk, and actors Bill Pullman and Melissa Leo.

McCall first appeared in the mid-1980s on TV with Edward Woodward playing him as a bit of an English dandy. In the film series, Washington plays McCall as a tad obsessivecompulsive, but not consistently. He’s the kind of guy who brings his own tea bag to a restaurant and arranges the cutlery just so. But, when prompted, his vision suddenly becomes hyper-clear and he meticulously pre-plans every step in taking down a room of thugs, often without a gun. He’s like Monk crossed with Sherlock Holmes.

In the first film, a hooker with a heart of gold pulls McCall out of retirement when she is badly beaten by her pimp. By the end, McCall has blown up most of Boston’s waterfront, exposed a nest of corrupt local cops and systematically executed every member of a Russian gang, even going to Moscow to finish the job.

The second film takes place sometime later, with McCall now a Lyft driver, selectively helping people he encounters. He’s kind to old people (a Holocaust survivor, for extra depth) and little kids, who adore him. He mentors a troubled teen (Ashton Sanders), hoping to steer him away from drug dealing and toward art school. Few people could pull off this cheesy sainthood like Washington, oozing charisma and self-assured masculinity.

When a group of smarmy, cocky Wall Street types abuse an intern during a coke-fueled party, Washington drives her to the hospital and then returns to wreak vengeance, slicing one dude with his own luxury credit card and then taunting his bleeding victims with “I expect a five-star rating.” It takes him a scant 29 seconds to destroy the room full of rich snobs; he times it, naturally.

The film somewhat confusingly toggles through various initial threads before landing on the main one — someone crucial to McCall’s murky past is murdered in Brussels and that reveals a barrel of bad government apples. The film thus strays far from its roots as a vehicle for McCall to be the avenging angel for a needy stranger. But we get to see McCall solve the crime from his Boston apartment by putting himself in the crime scene like an episode of “Crossing Jordan” and then avenge the death.

Fuqua is a lyrical director who directed Washington to an Oscar in “Training Day.” He’s not afraid to spend time in the still darkness with McCall and likes to focus on small moody elements, like rain hitting the gutters. But he also can deliver red meat: A sequence in which McCall fights off a passenger in the back seat of his car is a mini-masterpiece of taut, sinewy direction.

“The Equalizer” is a guilty pleasure for anyone who enjoys that oldschool, blue-collar American chivalric hero with a dark past.