It happens so fast, so abruptly, that we’re almost as rattled and surprised as the character it happens to.

Officer Mike Tan’s department-issued pistol goes off as he draws it out of its holster. He wasn’t pointing it, wasn’t in sight of the suspect he and his partner were chasing on a hunch. It was an accident, but in “A Shot Through the Wall,” we learn of the ramifications and consequences of this in-the-moment blunder.

The debut feature of writer-director Aimee Long is a somber, thought-provoking essay on policing, race, firearms and family. We see the a young man die from that random, careless shot, the defensive circling of the police department wagons that accompanies any “officer involved shooting” and the aching guilt of the man in blue who had no reason to have his hand on the trigger in the first place.

Kenny Leu of TV’s “The Long Walk Home” and “Kat Loves LA” is Officer Tan, a decent sort who dotes on his Chinese immigrant parents (Fiona Fu, Tzi Ma), counts himself lucky in his choice of fiancée (Ciara Renée) but probably wishes his partner hadn’t profiled those Black Brooklyn teens whom they’d expected to be in school. He really wishes one kid hadn’t fled, and Tan rues the day he chased the kid — because he fled a police stop-and-frisk — into an apartment building where the seemingly simple act of unholstering his firearm, under duress, ends one life and threatens to unravel his.

The story is told in flashback, the three months leading up to an introductory mother/son “cooking” opening scene — from the impromptu rookie-cop team’s chase and shooting, to the police union rep (Dan Lauria) who assures him “Everything’s gonna be fine,” to the blowback that turns that reassurance on its ear.

Suffice it to say there was cell phone video, the victim was Black and public tolerance for this sort of “mistake” by armed, aggressive police is at an all-time low.

Long tells this story entirely from the clumsy cop’s point of view, fleshing out the doting but nagging parents, the Black, mixed-race social worker he plans to marry and her resistance to being used in any “He CAN’T be a racist” media campaign thanks to the way her precinct chief dad (Clifton Davis, quite good) was showcased as the face of departmental tolerance for years.

Leu and Long play up the guilt Tan feels and the guarded way any human gesture — showing up at a vigil, trying to speak to the grieving mother — is impossible in any situation like this. The union and the lawyers won’t have it, the grieving families resist it and the media pokes a finger into any open wound it recognizes in media-mad New York.

Relationships suffer all up and down the line, knowing the “right thing” to say or do in the face of legal action, the fraught nature of race both within the NYPD and how it is viewed by the public

That said, “A Shot Through the Wall” pulls its punches, here and there, and doesn’t land a clean blow in the convoluted way Long tries to address institutional racism in this story. The ending is as abrupt as the shooting at the beginning, and entirely too pat to be believed. And layering in cooking in any Chinese-American tale is simply a cliche, at this point.

But Leu makes a solid lead, Renée a properly conflicted love interest and in Fu and Ma, Long gives Chinese-American parents who transcend the Hollywood stereotypes of such characters — at least somewhat.

Rating: unrated, violence

Cast: Kenny Leu, Ciara Renée, Fiona Fu, Tzi Ma, Dan Lauria and Clifton Davis

Credits: Scripted and directed by Aimee Long. A Vertical release.

Running time: 1:29