How do you feel about the prospect of retirement? Are you counting the days till you get away from your desk, free to roam the world or simply head up to your favorite stream to see how they're biting? Or is your identity tied up so much with your work that you dread the thought of giving it up? Sean Penn's sometimes lethargic but ultimately moving and lyrical "The Pledge" focusses on a police detective faced with these existential questions on the last day of his job. Considered one of the greats by his buddies on the Reno force, he is popular enough with his colleagues that he gets a slam-bang sendoff party on the day he is to call it quits. In the role of Detective Jerry Black, Jack Nicholson looks out the window and sees a man hobbling forward on a walker. He visits a nursing home only to find elderly men and women hooked to breathing devices or being aided to their seats. He is haunted by a vision that his real life is over on the day he hangs up his bulletproof vest. To add to his misery, he takes a sacred pledge thrust on him by the crucifix-carrying Margaret Larsen (Patricia Clarkson), mother of an eight-year- old girl who has just been found slashed and mutilated in the snows of Nevada, a promise that he will not give up until he finds the perpetrator of this loathsome act.

"The Pledge" is too phlegmatically paced to be of much interest to the crowd whose idea of a police drama is the "Lethal Weapon" series or who wonder whether any current movie can be even called a cop story without the presence of David Morse. But Penn's latest outing as a helmer would be pursued by fans of his similar achievements, his moody 1991 movie "The Indian Runner," about a man's attempts to get closer to his kid brother who had jsut returned from the 'nam, and his more recent incursion into the killing fields, "The Crossing Guard," about an individual's attempt to deal with the drunk-driving death of his daughter at the hands of a perp who had just been released from prison.

Somber but by no means lifeless, "The Pledge" is a piece about a just-retired detective so driven by his commitment that the book by the Swiss writer Frederick Durrenmatt (whose great drama "The Visit" is one of the most imaginative and compelling stage works of its decade) is virtually without humor. Adapted to the screen by Jerzy Kromolowski and his wife Mary Olson-Kromolowski, "The Pledge" is a framed story opening on a bizarre sequence that could have come from a post-lobotomy "All Flew Over the Cuckoo's Nest," then cutting between the grisly discovery of a girl's mutilated body and the joyful occasion of a popular detective's retirement bash. When a retarded Indian, Toby Jay Wadenah (Benicio Del Toro) confesses to the crime at the clever promptings of Detective Stan Krolak (Aaron Eckhart), the case is closed. But Jerry Black must have thought that Wadenah had watched Stephen Hopkins's "Under Suspicion" once too often and persuades chief of detectives Eric Pollack (Sam Shepard) to reopen the case.

Acting as a one-man squad who has dedicated his first year of retirement to solving the murder, he interviews a plethora of Nevadans such as the murdered girl's mother, Margaret (Patricia Clarkson), grandmother Annalise (Vanessa Redgrave), and the father of a girl similarly slain, Jim Olstand (Mickey Rourke). He is himself interviewed by a doctor (Helen Mirren) who catches some negative vibes from the detective and wonders whether he has become unbalanced by the search for a killer. When he discovers a waitress in the Nevada boonies, Lori (Robin Wright Penn) whose daughter is similar in age, hair color, and clothing to the ones who have been killed before in a similar style, he buys a gas station and settles in as a resident in Lori's backwater community.

Penn's film is a psychological study in obsession, a man's fixation on a single goal which, if affording no closure, could result in his turning from a top-level detective into a deranged and perhaps dangerous fellow. Willing to stop at nothing to solve the case, even using a lovely eight-year-old girl, Chrissy (Pauline Roberts) as bait without her mother's consent, Jerry conveys what could happen to any of us given the appropriate circumstances. A tribute to Penn and to his top-notch ensemble of actors, "The Pledge" breaks with the conventions of the cop dramas by featuring no explosions either verbal or chemical. The Canadian snows filmed by cameraman Chris Menges look both inviting and threatening while Jay Cassidy's editing and Hans Zimmer's violin- dominated soundtrack are unassuming.

Absolutely not for all tastes, "The Pledges" is lyrical, convincing, and an obvious labor of love for Penn and his stellar group of performers.