A four-decade practitioner of the Nichiren branch of Buddhism, Grammy- and Oscar-winning Herbie Hancock surprised with an admission that he was long addicted but now clean and that drugs had “brought out the exact opposite of the more empathetic and more compassionate in me.” These two feelings are notably lacking in the shuddery addicts who populate directors Josh and Benny Safdie’s telephoto guerrilla-documentary-style new narration. Heaven Knows What opened eyes and not veins at the Toronto, Venice and New York Festivals as well as SXSW 2015.

Co-scripted (with co-editor Ronnie Bronstein) by the brothers as well, with Benny also doing sound and co-editing, the ninety-three minutes is as visceral a look at the white, non-inner city, (mainly) heroin jones as Verdi Square’s The Panic in Needle Park but is even more an honest look at hustling and surviving on the mean streets of the New York where both films are set. Just how much is fictionalized this time is a toss-up, though mise en scène is location real and, tough for even hardened viewers, the tale strikes a true vein.

What contributes added authenticity is that, aside from Caleb Landry Jones as despicable Ilya, the players are real street folk “just acting for the first time,” amateurs naturally playing someone like themselves.

Central essential is Arielle Holmes as Harley, based on the first-time actress’ upcoming loose memoir, Mad Love in New York City, written for the most part in computer shops on the directors’ suggestion and commission though interrupted by a stint at Bellevue following her failed suicide. Nineteen when they had initially met, she worked -- most improbably, given security checks -- in the midtown Diamond District about which the Safdies were doing research for a different feature.

Older Diana (Diana Singh) rents capsule bunk beds and bathroom privileges and ineffectively mothers the street addicts. The rest are kids, with no families or origins or directions or homes. Most everything in their existences revolves around scoring smack, in which they are like animals -- the City’s pigeons are an apt example -- who strut and scrounge for food every single waking moment.

They beg for rent (or drug) money, panhandling, “spanging,” writing lies on cardboard for sympathy; they steal 5-hour ENERGY supplements and sundry other carry-ables from convenience stores for fencing to kiosks or, a Federal offense, make off with mail while carriers are inside buildings. Ignored or avoided by jaded or blasé passersby--though a yarmulked Jew volunteers an unsolicited twenty dollars “to get high”--some live in open spaces, in doorways or over heat exhaust gratings in cold weather or in parks and band shells where they gather to get stoned in company or for quickie open sex. Alcohol looks to be absent.

SPOILER ALERT

Possessed or obsessed by an amour fou, Harley is certain she loves Ilya (the model for whom OD’d before shooting began but was revived) and, in despair at his abuse and indifference, slits her wrist to prove it. Tall massive Skully (gore rapper Necro) insists that she is better than her surroundings, but she is not interested in his friendship or more and instead becomes involved with spacey glib drug dealer Mike (Buddy Duress). Their relationship offers a measure of protection and stability, until Ilya shows up again, walking off with and hiding her duffel bag for starters.

Harley says that hers is love forever, but what it really is, is insecurity and a dangerous psychological dependence that leads her back to him, to accepting him back, and to inevitable further disappointment. Ilya cannot change, nor does Mike; one hopes that Harley will.

Sean Price Williams’ cinematography and a Debussy-derived electronic score from Isao Tomita increase the feel of frantic impermanence, of life for- and in-the-moment on the edge. Other sides of this urban story, of violence, prostitution, heroin and crack cocaine in the ghetto, are not here but lurk in the wings waiting for their chroniclers.

(Released by Radius and rated "R" for drug use throughout, pervasive language, disturbing and violent images, sexuality, and graphic nudity.)