With the exception of a beautiful baby boy, nothing belongs to the title character of “Alanis,” not even her name, a cover she developed to make her more attractive when she started turning tricks on the streets of Buenos Aires. Hard-won agreements with clients about services she’ll perform are always at risk of slipping through her fingers like quicksand (when one pitches $800 split between $300 for a room and $500 for her, he jokes about reversing the equation right before the hotel door) and her living arrangements are always in flux, coming to depend on her aunt’s clothing store for a floor to sleep on after being unceremoniously locked out of an apartment she shared with a fellow sex worker.

Anahí Berneri’s fifth feature feels like an avalanche, made all the more powerful by the craft with which the writer/director puts into every frame trapping Alanis in a cage with bars she cannot see. A clear-eyed look at a social safety net with gaping holes in her native Argentina, Berneri spins a ferociously cascading drama out of simply looking at the plight of Alanis, a single mother who usually feels more exposed when off the clock from her job as a prostitute than on it. Always seemingly able to find takers to babysit her adorable son Dante, finding support for herself is another matter entirely, as Alanis has been consigned to the shadows of the city at the hopelessly old age of 25, slinking around in a red skin-tight outfit that can be considered a négligée or a dress, depending whether she’s inside or out of her apartment. When two police task force investigators posing as clients bust into her place as part of a crackdown on brothels with the aim of protecting the women that work their from their pimps, they inadvertently set off a chain of events for Alanis that plunges her deeper into desperate straits.

The central role is thoroughly inhabited by a cunning Sofia Gala Castaglione, conveying a street savvy that may prevent her from fully realizing what she’s up against as she visits government offices either to be questioned in criminal matters or to seek recourse for crimes committed against her, but radiates a toughness that allows the various setbacks to roll off her to avoid despair and keep pressing ahead. In early scenes, Berneri shrewdly uses pointed angles to capture Gala’s body, covered with pockmarks and tattoos to spell out a history of wear and tear that led Alanis to where we find her in a dank flat, occasionally able to dominate a situation out of a fierce sense of self-preservation, but largely cut out of scenes with great implications on her future. Frames are also frequently split throughout the film to expose the distance between how the world sees Alanis through reflections in windows and mirrors versus how she actually exists with constantly provocative cinematography from Luis Sens, but Berneri achieves something rare in creating a character study with a distinctive style yet never removed from the stark reality it presents. In tackling just how easy it is to fall through the cracks, “Alanis” is entirely gripping with a lead that may have trouble finding a place to live on screen, but will likely reside in the hearts and minds of anyone who experiences her story.

“Alanis” does not yet have U.S. distribution. It will next play at the San Sebastian Film Festival on September 22nd, 23rd and 24th.