A terminally ill hit-man decides to go out with a bang — a couple of bangs — by executing the guys above him on Taiwan’s “Most Wanted List” in “The Pig, the Snake and the Pigeon,” a new thriller from the director of “Once Upon a Time in Shanghai.”

Fair enough, simple enough, you say. As did I. Our killer, formerly known as “The Kuilin Kid,” has to track down mobsters in hiding, manage his illness and keep the cops at bay — especially the dogged investigator he blinded in a brutal chase and fight a few years before — to complete his mission.

But writer-director Ching-Po Wong throws a curveball in the third act that is positively Tarantino-esque. Even if you figure you’ve “seen it all,” like me, there are twists and moments that will make the viewer go from “Wait, say WHAT now?” to chortling at the audacity.

Yes, it’s a bit long and by the way, that third act is so over-the-top that it goes well past straining credulity and into “Oh come on, now.” The finale, informative about the Taiwanese justice system, is more bitter than touching.

But for those looking for a conventional thriller that delivers, and then turns into “something completely different,” this one fills the bill.

We meet “the kid” at a mobster’s funeral outside of Taipei. We learn how the guy died from a mob-punk fanboy Goldie (Tzu-Chuan Liu) who tells this gauche, grinning goof with no table manners what “The Kuilin Kid” did. No, the goof in the ill-fitting suit can’t give Goldie a lift back into town.

“I’m Chen Kui-lin,” he (Ethan Juan) tells the lad. “I have a real name. Stop calling me ‘Kuilin Kid!'”

He then finishes “the job” by brazenly shooting another mobster at the funeral.

Here’s a buy-in moment for genre fans. A mob funeral with “over 800” made men, and the only one with a gun is the assassin? Nobody’s gutsy enough to take one for the boss, or gang tackle the killer?

The cops have been monitoring this ceremony, and one (Lee-zen Lee) is a more than a match for our sprinting escapee. Or maybe just a “match” as they brawl. OK, not quite a match, as Chen Kui-lin takes out the detective’s eye to break free.

Years later, a now-bearded Chen Kui-lin is long on the lam, when a “pharmacist” whose side hustle is mob doctor (Cherry Hsieh) gives him the bad news. He’s got just a few months to live.

“Rather than dying like a street rat,” she says (In Mandarin with English subtitles), “you could act more honorably…die with a little dignity.”

After trying and failing to turn himself in, the guy who wanted to make sure that fan at the funeral at the beginning of the story remembered his name wants to leave a little notoriety behind. He will hunt down killers more notorious than he is and dispatch them.

Our writer-director handles the “Hunt for the mobster/victims” scenes with skill — a wary stake-out here, a suspenseful straight-razor shave there.

But just as we figure the picture has settled into what it’s destined to be, that third act takes a detour through Tarantinoland, which is all I’ll say about it.

Juan makes the move from supporting roles in assassin movies like “The Assassin” to swaggering, determined and resigned killer-for-hire with ease. He’s got great presence and is credible as a brawler, a sprinter and a man having an existential crisis, which comes to a head in that lulu of a third act.

Hsieh makes her mob doctor morally-conflicted to the point that when Kui-lin kidnaps her kid to make her give up information, she takes it in stride as a sort of just deserts. Gingle Wang ably plays a damsel in the clutches of a mobster (Ben Yuen, perfectly vile) and thus in distress.

Ching-Po Wong gives us a taste of Taiwan in his thriller’s varied settings, never really breaking the spell of following our anti-hero to focus on the cops chasing him. A horn-flavored jazz-pop score sets the underworld on the move mood.

As long as you’re not squeamish about a bodycount — not everybody who “gets it” deserves it — and how that’s papered-over here, this “leave the world better than you found it” parable, with its “notoriety is still fame” messaging makes for a pulse-pounding surprise.

Rating: TV-MA, lots of violence, near nudity

Cast: Ethan Juan, Cherry Hsieh, Ben Yuen, Gingle Wang, Chen Yi Wen and Lee-zen Lee

Credits: Scripted an directed by Ching-Po Wong. A Netflix release.

Running time: 2:14