Veterans of the Honk Kong martial arts movie scene star in “Time,” a tale of martial arts assassins in retirement, a comedy that has ties to “Kung Fu Hustle” and “Shaolin Soccer” and enough promising ideas passing in front of the lens that you keep waiting for a big finale that never comes.

Here’s what I mean by “promising.” How would low-rent contract “muscle” make ends meet in its dotage? Maybe hired killers could take on freelance work from online ads — aged contemporaries who know “There’s nothing worse than being bedridden (in Cantonese with English subtitles, or dubbed).”

The killers would become “assisted suicide” contractors. That’s the best idea “Time” loses track of over its 98 minutes.

A kick-ass hit-man/woman trio, “The Invincible Trio,” used to rule Hong Kong’s underworld back in the day. We catch them in their prime in an old-fashioned slo-mo, freeze-frame to animated still brawl in the opening scene, which has the groovy music and cartoonish facial expressions that characterized the Bruce Lee-and-earlier era in kung fu cinema.

These three — Chau, Chung and Fung — were unbeatable, with the cold-blooded Chau usually delivering a throat slitting coup de grace via a “the Lethal Slash” of his curved blade.

But that was decades ago. Chau (Patrick Tse) is now a wizened noodle cook, too slow with his handmade pasta to keep up with his nephew’s new automatic noodle maker.

Fung (Bo-Bo Fung) still sings, which she has to do to support her deadbeat son, daughter-in-law and grandson. Her moves are pretty rusty and she’s looking at assisted living options.

And roly-poly Chung (Suet Lam), their driver and sometime rescuer, has gotten even rounder and is diabetic, short of breath and enamored of a sex worker one third his age.

A DJ’s message on the radio gets the band back together. But these assignments are sad and the infirm, aged and sickly or just lonely clients who hire them are even sadder.

Fung lives by the same aphorism she tells audiences (older) for her cabaret act. “Life is short, death is sure.” Live while you can. But these new clients helping them pay the bills? They’re a bummer.

“Don’t make my wife wait,” one wealthy, aged widower pleads.

That whole story thread is abandoned when Chau takes one job too many, one hit that’s way out of the ordinary. Tze Ying (newcomer Suet-Ying Chung) takes off her Beats, snaps a selfie with the old, ponytailed hit-man, all dressed in black at her door. He yanks the phone out of her hands, ignores her “I want to DIE” pleas, and flees.

But she’s got the drop on him, snatching his phone as he took hers. She’s determined to make him help her with her problem. And she’s maybe 16, 17 years old.

First-time feature director Tsz Pun Ko and his screenwriter find a few funny things to do with this situation, confronting the boy who dumped this lovesick teen, for starters.

Hey, the kid protests, “I took her to a BTS concert already.” He’s paid his dues. He’s entitled to break up.

Most of the attempted humor here is about clueless old folks still able to get a dirty job done and the enervating shrug of deciding whether or not to just “give up” themselves

The fights are fun, but far between.

If you’ve watched Hong Kong gangster movies or martial arts comedies, you’ve seen these folks in their prime. There’s not inherently sad in seeing them now, as Tse still has the air of menace, Lam still a waddling punch-line and Fung still “the girl.”

But the generically-titled “Time” never finds many laughs and never finds its way through these twilight years, when the “invincible” are more vulnerable, but still need the work.

Rating: TV-MA, violence, blood, sexual situations

Cast: Patrick Tse, Bo-Bo Fung, Suet Lam and Suet-Ying Chung.

Credits: Directed by Tsz Pun Ko scripted by Ka-tung Lam. A Netflix release.

Running time: 1:38