'American Crime' is tough viewing

Ellen Page (left) and Catherine Keener in Showtime's "An American Crime." (SHOWTIME NETWORKS)

"An American Crime" is one of the most disturbing made-for-cable movies I've ever endured. I'm not sure I would have made it to the final credits, if it weren't my job. Which isn't to say that this Showtime drama, which premieres tonight at 9, is poorly made or inadequately acted. The fact that the story is so excruciating to watch testifies to the power of its grim atmospherics and the strong leading performances by Catherine Keener and Ellen Page.

But you need to be a committed student of the human condition, and willing to see people at their very worst, to find the value in "An American Crime." Directed by Tommy O'Haver, the movie is based on the true story of Gertrude Baniszewski (Keener), a single mother of seven in Indiana who systematically tortured a 16-year-old girl under her care in 1965. The girl, Sylvia Likens (Page), was kept in the Baniszewski basement, starved, beaten, burned by cigarettes, and branded on her torso for weeks, eventually abused not only by Gertrude but by her children and their friends. The crime, notorious for its heartlessness, was also dramatized in Jack Ketchum's 1989 novel "The Girl Next Door" and a 2007 film of the same title.

Keener's Gertrude is quite obviously a mess, and it's painful to see Sylvia's naive carny parents leaving her and her sister, Jenny, in Gertrude's home. A cough-syrup addict and a hard drinker, Gertrude can hardly take care of her own brood, which includes a newborn whose father (James Franco) is a young hood. She takes in Sylvia and Jenny for $20 a week, and at first all goes smoothly. But Gertrude's oldest, Paula, is having an affair with a married man, and Gertrude directs her frustration about that onto Sylvia. Well-played by Page with gentle introversion and stoicism, Sylvia becomes the perfect scapegoat.

Gradually, Gertrude's children join in against Sylvia, and the movie includes a number of troubling scenes of both violence and implied violence. The script, by O'Haver and Irene Turner, vaguely implies that intense financial strain is leading the family to gang up and turn on one of its weaker members - a sort of animal pack phenomenon. But it never commits to any one explanation or theory, which is a good thing. A more facile movie might have had a psychologist character on hand to reduce the Baniszewski's group violence to a single factor. "An American Crime" simply dramatizes the horrifying events and the human potential for cruelty and leaves the analysis to us.

The movie is framed by a trial, in which characters take the stand and Bradley Whitford's prosecutor asks them questions. The device offers some welcome relief from the Baniszewski house, which is effectively run-down, drab, and claustrophobic. But the courtroom scenes are blandly written, and Whitford has no opportunity to be anything more than the generic righteous lawyer. The true potency of the movie is in watching the crime unfold under Gertrude's guidance, a conspiracy of desperation led by a demented mother.

There are moments when Keener veers into "Mommie Dearest" territory, but for the most part she keeps Gertrude low-key enough to seem real. The impact of her savagery toward Sylvia isn't dulled by camp. And, as Paula, Ari Graynor delivers one of the movie's most affecting performances. Graynor, who played Meadow's manic-depressive roommate on "The Sopranos," convincingly conveys the contradictory way a person can compensate for powerlessness by making someone else powerless. She shows us how innocent teenage frustration can turn into something deeply tragic.

Matthew Gilbert can be reached at gilbert@globe.com. For more on TV, visit boston.com/ae/tv/blog.