In her juiciest roles, the actress Diane Venora has played characters faced with unconscionable decisions. She burst onto the New York theater scene in the 1980s as the first female Hamlet in the history of the New York Shakespeare Festival, but to film buffs, she may be most vividly remembered for her performance in Michael Mann’s 1995 crime epic “Heat,” in which she played the scarred and dejected wife of an obsessed workaholic, played by Al Pacino. In both roles, she took her characters to the brink; as Hamlet, she considered the prospect of suicide, and opposite Mr. Pacino, she struggled to cope with the realization that the man she loved could never love her back.

Between those two performances, Ms. Venora crafted perhaps her most critically acclaimed role, as Chan Parker, the wife of famed jazz musician Charlie Parker, in Clint Eastwood’s 1988 biopic “Bird.” The performance, which earned her a Golden Globe nomination, was another vintage Venora role: the wife as enabler. Chan was too caught up in her love for Charlie and his music to encourage him to kick his dependency on drugs.

Despite this history, something about Ms. Venora’s performance as the tormented mother of a degenerative addict in Monty Lapica’s “Self Medicated,” which arrives in New York theaters on Friday, makes it more haunting than anything she’s done before. Young Andrew (Mr. Lapica) is perilously close to rock bottom, driving drunk and verbally abusing his harrowed mother, when his world is upended one night as black-clad men snatch him from his bed and drag him out of the house. Louise (Ms. Venora) watches in horror, knowing that she is the one who called these men and authorized the abduction in hopes of getting her son to a treatment center. A shattered shell of a woman, she sobs and moans as Andrew pleads for help. Before long, she has returned to her array of prescription drugs to dull the pain of a dead husband and what she deems a lost child.

“You have a woman who’s destroying her life without knowing it,” Ms. Venora said recently. “She’s trying to make sense out of this life, but she lacks authority as a parent and something is compromising the soul of this character. That scene in particular, when he is dragged out of the house, was very painful. All I remember was thinking that I have to project this terror of a woman trying to save her son’s life, a woman who is so terrified that she has been rendered completely impotent as a mother.”

Ms. Venora, who was attracted to the project by Mr. Lapica, the 24-year-old who wrote, directed, and stars in the film, said there was a “streak of youth” to the material that intrigued her, a unique tone and pacing that made “Self Medicated” about something greater than just one dysfunctional mother-son relationship, or one young man’s ordeal in a militarystyle treatment facility. Her performance is rendered all the more moving by how much pathos she is able to bring to the character of Louise in only a few emotionally destructive scenes.

“One thing you learn is that there’s no such thing as small parts,” she said, recalling her formal New York acting training. “Juilliard trains you to go as high as you can go and as low as the depths will support you and then you’ll have a memorable performance. I’ve managed to learn how to turn on a dime, to evoke the same emotions and conflicts in five lines as you can in 25 lines, if they decide to trim the script at the last second. It’s something you have to be able to do.”

It’s no surprise, then, that so many of Ms. Venora’s roles, even her smaller ones, have resonated with critics and filmmakers alike. In the next two years, she will be seen on-screen in more than five films, movies ranging from crime mysteries (“The Ministers”) to funeral dramas (“Childless”) to mob thrillers (“Stiletto”). And although each role varies in size, she said she goes through the same process of cutting to the deeper truth, of discovering who this character truly is, and how they fit into the world beyond the script. Sometimes, though, that’s a place actors don’t like to go.

“You have to think of something beyond yourself. The character is bigger than the actor,” she said. “Take this mother. There’s a secret to her, something that’s never mentioned in the script. A thought she’s trying to defend, to fight and fend off — that if her son’s like this, then someone somewhere must be responsible. But she refuses to look at herself, and she uses medication to fill in for the emptiness and loneliness and the guilt. And that’s a scary place to be, but it’s the only place that true acting can take us.”

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Late Friday, the announcement came down that director Ang Lee’s forthcoming film, “Lust, Caution,” which is already being marketed aggressively in advance of its September 28 release, was slapped with an NC-17 rating by the Motion Picture Association of America — a rating with implications far beyond patrons being carded at the door. Newspapers often refuse to carry ads for NC-17 films, many theater chains won’t carry NC-17 titles, and some video store chains will refuse to keep such works in stock.

But unlike some other recent films, which have abandoned the NC-17 rating and gone out to the public as “unrated” in the hope of avoiding such entanglements – Darren Aronofsky’s “Requeim for a Dream” comes to mind — “Lust, Caution” is being released by Focus Features, a subsidiary of Universal Pictures, which is an MPAA member and must release rated titles. But rather than trim the film to secure an R rating, Focus is standing behind Mr. Lee’s final cut, and reportedly will not change a frame.

So the question now becomes: How will a highly anticipated film by an Oscar-winning director, about a young Chinese woman in Japanese-occupied Shanghai during World War II who becomes the center of a plot to seduce a married enemy collaborator, be received by the public? If “Lust, Caution” is released to critical acclaim, might it soften the MPAA’s grip on the industry — or at least strengthen the push for a viable adult rating in an industry that would seemingly prefer that people stab each rather than make love?

ssnyder@nysun.com