Angela Bettis stars in “12 Hour Shift,” a Magnet release.  

Reel Time sig Lee

The number of hours I spent wandering hospital corridors as a child is incalculable; probably far more than most kids my age, and probably far fewer than my distorted memory suggests. Between the emergency room admitting area and the 24-hour cafeteria with snack-filled vending machines and automats offering pre-made sandwiches, I must have spent enough time there for my mother to allow her 6-year-old to sit unaccompanied in a waiting room filled with solemn strangers. From what I recall, the nurses always showered me with kindness and enthusiasm, providing a sharp contrast to my mother’s engrained angst whenever my father’s health started failing.

Although I am certain some of those nurses took the time to calm my fears with words of encouragement, nothing could keep me from developing both a cyclical streak of hopelessness and a lifelong dread of hospitals.

“12 Hour Shift” is a quirky, dark comedy written and directed by Brea Grant. The film was released Oct. 2 by Magnet Releasing and is available through video on demand platforms such as Vudu, Fandango and Amazon Prime. At first glance, it could easily be mistaken for a slasher film due to its gratuitous visceral violence. The only horror here, though, is the seemingly endemic inhumanity of a group of individuals involved in a black-market organ-harvesting scheme.

Set in 1999, the film follows Mandy (Angela Bettis), a nurse in an Arkansas hospital, over the course of one 12-hour graveyard shift. The viewer is presented with some crucial facts up front: Mandy is a drug addict and she is part of an organ-trafficking ring working out of the hospital. The members of this nefarious group each have very specific duties to keep the process compartmentalized. Mandy apparently multitasks, though, when necessary. When a dying patient is selected for harvesting, Mandy hastens their demise as necessary. Her preferred method of beckoning the Grim Reaper is an injection of bleach. Once another team member has removed the vital organs, Mandy walks them out of the hospital and hands them off to someone else who will transfer them to the recipient.

In “12 Hour Shift,” the runner is Regina, Mandy’s “cousin.” Unfortunately, Regina — who is new to the job — is neither smart nor stable. On a loading dock outside the hospital, Mandy passes a bag full of organs to Regina, who promptly leaves it sitting on the ground and takes off with a cooler containing two cans of soda. When her boss Nick (Mick Foley) discovers her mistake, he threatens to take Regina’s kidney if she can’t come up with a replacement.

Regina’s incompetence derails the entire operation with alarming swiftness, forcing Mandy and Karen (Nikea Gamby-Turner), another on-duty nurse and a co-conspirator in the scheme, to make increasingly dangerous choices to keep from getting caught. Thrown into the mix are a variety of unpredictable variables such as Jefferson (David Arquette), a death row inmate who is brought into the hospital after trying to commit suicide; Mr. Kent, a hypochondriac demanding a room though he has no presenting symptoms; Janet (Brooke Seguin), the lead nurse on the floor who exhibits a complete lack of compassion for her staff; and Officer Myers (Kit Williamson), who is as awkward at flirting as he is at being a cop.

“12 Hour Shift” is an ever-expanding universe of crises, starting with personal problems such as addiction and workplace rivalry and increasing in scope and significance to contemporary social issues such as euthanasia and capital punishment. Though the tone is macabre, the narrative template borrows heavily from farce, as the characters continually make decisions that propel them toward absurd and seemingly inescapable situations. The amount of gore alone gives the movie a grindhouse edge, but somehow “12 Hour Shift” feels less exploitative than intelligent.

According to Grant’s production notes, a mix of 1990s news stories and urban legends served as inspiration for “12 Hour Shift.”

“In the mid-90s, the East Texas news stations were filled with the story of a nurse who killed a few patients using bleach,” Grant explained. “It’s hard to remember what was fact and fiction at the time. I was a teenager in a small town and the actual news story stays mixed up in memories with urban legends of organ selling, drugs, and that one story about a woman ending up in a bathtub full of ice after her kidneys were stolen.”

In her film, Grant sought to blur the harsh reality of opioid use, lack of small-town services, the understaffing of a hospital with the dark glamour of an urban legend involving criminals and lost kidneys.

“But the main thing I wanted to do was to show something that we don’t get to see often enough in films — a female anti-hero,” Grant said. “We are often cheering for the wise-cracking, angry-but-always-right, sour leading man. I wanted to show that same type of character as a woman. I wanted her to make mistakes and be cruel but still be a person worth following.”

Grant delivers a quirky tour de force populated by amoral characters who are only separated by varying degrees of wickedness. Mandy, even when she’s impaired by her addiction, remains level-headed and ingenious, committed to cleaning up every mess and maintaining as much control over the situation as she can. Regina, on the other hand, is walking anarchy, spreading chaos and trauma in a homicidal bender while displaying nothing but bewildered indifference. Both Mandy and Regina — along with the other organ traffickers — exhibit a common thread of cold-bloodedness in their impersonal assessment of moribund patients as biological warehouses filled with valuable spare parts. Mandy, though, shows a glimpse of compassion in selecting viable candidates. She might well be a descendant of the Brewster sisters from “Arsenic and Old Lace.”

There is an elegant dichotomy beneath the grittiness and gore of “12 Hour Shift,” as the preposterousness of Regina’s brutal, blundering attempts to condense the complex process of organ trafficking clashes with the equally chilling meticulousness of institutionalized suffering in a system that disallows euthanasia. It’s ugly enough to make you squirm and suspenseful enough to keep you engaged. While Grant’s film might not induce nightmares right away, you might not sleep so easily the next time you spend a night in the hospital.