By David Kronke TV Critic

You can have your "Hostels," your "Prom Nights," your "Saws." "An American Crime," a shocking docudrama based upon an equally shocking 1965 crime in Indianapolis, will scare and disturb you in ways that may be difficult to shake off.

The film debuted last year at the Sundance Film Festival; for understandable reasons, it did not secure distribution. The duty was left to Showtime to premiere it in America.

Catherine Keener (a recent Oscar nominee for "Into the Wild") stars as Gertrude Baniszewski, an asthmatic single mother with a host of children and a young lover she can't control. When Lester Likens (Neck Searcy), a traveling carnival midway booth operator, asks her to watch his teen daughters Sylvia (Oscar nominee Ellen Page, a long way away from the winsome "Juno") and Jenny (Hayley McFarland) for $20 a week, Gertrude hungrily accepts the cash.

A future payment doesn't arrive on time, so she beats Sylvia.

Gertrude's daughter Paula (Ari Graynor) complains about Sylvia, which prompts further beatings and even excruciating moments of torture.

She even invites her children and those in the neighborhood to become willing participants in the horrific abuse; neighbors, on the other hand, hearing Sylvia's screams, refuse to get involved.

Director/co-writer Tommy O'Haver (whose somewhat unlikely previous work includes the children's film "Ella Enchanted") and his collaborator on the screenplay, Irene Turner, examine the cycle of violence that plagues the underclasses: Both Gertrude and Paula are shown as victims of violence, which spurs them to want to take control of and wield power over something, anything, anyone. And Sylvia proved a tragically convenient target.

Alan Lazar's sometimes-trite score occasionally cheapens the intensity of the drama, as does an occasional flourish of artistic license.

But Keener's chilling performance as the distraught and sadistic Gertrude hits virtually no wrong notes - this is the ultimate in roles almost impossible to humanize, and yet Gertrude remains more pathetic than monstrous. Page is heartbreaking as Sylvia, an innocent bystander who has no idea why fate has singled her out for such incomprehensible cruelty.

Brutality of this measure simply can't be understood by most people. But it is the audacious daring of "An American Crime" to attempt to make sense of it and explain it to an audience, and it does so with an unnerving skill, which, no doubt, is why few will ever see it. Those who do, for better or worse, won't soon forget it.

David Kronke, (818) 713-3638 david.kronke@dailynews.com www.insidesocal.com/tv/

review>

3 1/2 stars

AN AMERICAN CRIME >What: Docudrama depicting a horrifying 1965 crime involving an overburdened single mother (Catherine Keener) and a young boarder (Ellen Page).

\>Where: Showtime.

\>When: 9 tonight; also 11 p.m. Thursday.

\>In a nutshell: Utterly disturbing, well-acted examination of violence begetting violence.