By OnMilwaukee Staff Writers   Published Jan 26, 2001 at 7:51 AM

Sean Penn is without a doubt one of the most talented people in the movie business. His work in front of the camera is nothing less than extraordinary. From "State of Grace" to "Carlito's Way" to "Dead Man Walking," Penn has turned in some of the finest acting in the last decade.

Always a Hollywood outsider, Penn has said that soon he will quit acting altogether and just direct. The good news is that his first two efforts behind the camera, "The Indian Runner" and "The Crossing Guard," are unconventional and absorbing dramas. Penn likes to go places others fear.

Penn's third trip behind the camera, "The Pledge," is his best yet as a director. It's dark as night and not always pleasant to watch, but it's a superb psychological character study that pulls no punches. If you're the kind of person that cites "Seven" on your list of favorite movies, it should be right up your alley.

Jack Nicholson (who also starred in "The Crossing Guard") stars as detective Jerry Black. Jerry is attending his own retirement party when news hits that the body of a little girl has been found. He leaves the party and goes to the scene of the crime with his partner, Stan Krolak (Aaron Eckhart).

The girl has been sexually assaulted and brutally murdered. The cops think a mentally disabled Indian Toby Wadenah (Benicio Del Toro) did it because he was seen leaving the crime scene. Krolak gets him to confess to it, and almost instantly Toby commits suicide. As far as the police are concerned, the case is closed.

But Jerry is not convinced. After breaking the news to the girl's parents, in a heartbreaking scene, he promises her mother (Patricia Clarkson) that he will find the killer. He becomes consumed with discovering the truth, at whatever the cost. His own investigation leads him to believe that the killer is still out there and responsible for at least two other similar murders.

In a desperate move, Jerry buys a rundown gas station on a lonely stretch of highway. Based on the locations of the killings, he concludes that the killer will travel in front of the station. Using a few clues he has gathered, Jerry begins his mission of keeping the promise.

"The Pledge" is not a movie for the masses. Penn plunges the audience into the depths of human depravity and never comes up for air. Without ruining the ending, let's just say that in the real world justice is not always done. But Nicholson is phenomenal and his journey is gripping and tragic.

The movie has plenty of other things going for it. The supporting cast, in addition to Clarkson, Eckhart and Del Toro, is fantastic. Showing up to offer their support is Robin Wright Penn, Helen Mirren, Vanessa Redgrave, Mickey Rourke, Sam Shepard, Harry Dean Stanton and Tom Noonan.

Also worth mentioning are the haunting score by Hans Zimmer ("Gladiator") and Klaus Badelt and gorgeous cinematography from Chris Menges ("Michael Collins").

You'll have to have a strong stomach to sit through "The Pledge." Surely many will hate it for it's bleak story and almost hopeless outlook, but there's no denying that it is an extraordinary movie.

Grade: A-

"The Pledge" is now showing.