After the honorable failures of The Indian Runner and The Crossing Guard, Sean Penn makes a quantum leap forward with his third directorial effort, The Pledge, an intriguing murder mystery that's also effective as a psychological character study. Heading a splendid cast, Jack Nicholson, who also starred in Crossing Guard, gives a riveting performance that dominates every frame of this broodingly intense drama. However, deliberate pacing and a downbeat tone will severely curtail commercial acceptance by mainstream audiences, relegating the film to the more specialised circuit.

Penn brings to his direction the same visceral intensity and raw emotionalism that define his acting. His movies are marked by a claustrophobic mood with a ponderous style that often prevents audience's involvement in his narratives. His debut, Indian Runner, inspired by Bruce Springsteen's Highway Patrolman, extended a five-minute ballad to a two-hours-plus biblical allegory about two brothers.

Crossing Guard, Penn's second film, examined the sorrowful journey of two men in the aftermath of a tragedy. The Pledge treads similar thematic turf. Crossing Guard was a study of an obsessive father who won't give up until he confronts the man who killed his daughter in a drunk-driving accident. The new film is about an obsessive detective whose investigation of one girl's murder leads to his becoming a surrogate father to another girl.

As in the past, Penn reaches for the ragged emotionalism that characterises the work of John Cassavetes, his obvious model. However, in The Pledge, Penn the director shows new, encouraging signs: a closer attention to narrative and character development.

The first scene depicts Nevada detective Jerry Black (Nicholson) as he lingers at his office one last time before being dragged to a surprise retirement party by his boss, Pollack (Sam Shepard). Humbled by his peers' generosity, he accepts their gift, an airline ticket for a fishing trip in Mexico. However, when the body of a murdered girl is discovered in the snow-blanketed mountains, he's unable to step aside. "I've got six hours left on the clock," he exclaims, following in the tradition of ageing American screen heroes who get involved in one last (often fateful) job before their retirement.

Jerry becomes more committed to the case after meeting Ginny's distressed mother (a splendid Patricia Clarkson). In a scene imbued with religious symbolism, he pledges to find the killer "on my soul's salvation".

Following through, Jerry observes the interrogation of Wadenah (an unrecognisable Benicio Del Toro), a suspect who was identified while fleeing the scene of the crime. In one of the film's most disturbing moments, detective Krolak (Aaron Eckhart) wrenches a questionable confession from the simple-minded ex-con, who then shockingly blows his brains out.

The case is closed, but Jerry - and the audience - can't shake his instinct that an innocent man was forced to confess. Obliterating any other interest, he begins a tortuous inquiry into the murder, with no leads and no authority. In a manner of noir's haunted and revengeful protagonists, Jerry finds a mission that lends new meaning to his otherwise solitary existence.

Jerzy and Mary-Olson Kromolowski's dense script, based on Friedrich Duerrenmatt's novel, is constructed as an intricate puzzle that's composed of numerous sub-plots and roles. Along the way, Jerry visits Ginny's loving grandmother (Vanessa Redgrave); Ginny's schoolmate, who provides clues about their conversations; and a psychiatrist (Helen Mirren), who's asked to interpret Ginny's drawings.

Though very much a study of one man, the film is enriched by Jerry's varied encounters with Cage (Harry Dean Stanton), who sells him his shabby gas station; Olstand (Mickey Rourke), the father of a long-missing girl who looked like Ginny; and Larson (Michael O'Keefe), a tough cop who investigated a similar crime.

The Pledge may be one of Hollywood's most bizarre serial killer sagas, one more concerned with the troubled persona and tangled relationships of its investigator than with a forthright resolution of its mystery, as is the norm of this genre. The central segments describe the evolving romance between Jerry and Lori (Robin Wright Penn), a local waitress and single mom who's been battered by her ex-husband. Evidence that Penn is more intrigued by probing Jerry's psyche than by the killing is revealed in a strategic scene, in which the psychiatrist turns the tables and puts Jerry under scrutiny with intimate questions about his sexuality.

It's a tribute to Penn that both moral ambiguity and genuine suspense prevail to the end. The film starts off with a brutal killing and sustains a threat of possible violence throughout, even in its gentlest episodes. At the same time, the closure, which defies generic conventions, will frustrate viewers used to neatly-resolved suspense films.

Though The Pledge is also problematic from a commercial standpoint, it's not as rambling, overbearing and painful to watch as Penn's former work. Artful cross-cutting, which has burdened Penn's work, is put to a much better use here, particularly in the last reel, in which Jerry manoeuvres a complicated scheme to entrap the killer. Penn's acting roots continue to be apparent in his tenacious focus on his high-calibre cast. The fascination with which he observes Nicholson's frightening intensity is conveyed by numerous mega close-ups.

Nonetheless, unlike Crossing Guard, in which Nicholson struggled with a pretentious script, he renders here a multi-layered characterisation that radiates his usual eccentricities but also kindness and repressed yearning. The Pledge benefits immensely from Chris Menges' astute photography of British Columbia (standing in for Nevada), Jay Cassidy's meticulous cutting, and Hans Zimmer and Klaus Badelt's evocative music.

Pro cos: Morgan Creek and Franchise Pictures; US dist: Warner; Int'l distrib: Franchise Classics; Exec prod: Andrew Stevens; Prods: Michael Fitzgerald, Sean Penn, Elie Samaha; Scr: Jerzy Kromolowski and Mary Olson-Kromolowski, based on a novel by Friedrich Duerrenmatt; Cinematographer: Chris Menges; Pro des: Bill Groom; Ed: Jay Cassidy; Music: Hans Zimmer and Klaus Badelt; Main cast: Jack Nicholson, Robin Wright Penn, Patricia Clarkson, Benicio de Toro, Aaron Eckhart, Helen Mirren, Michael O'Keefe, Vanessa Redgrave, Mickey Rourke