At one point in Dennis Lehane’s 2001 novel Mystic River, a police detective asks his colleague as the murder they are investigating takes an absurd turn: “What, we’re starring in a movie now?”

The remark proved prescient. Two years later, the novel was adapted for the big screen by Clint Eastwood. The 2003 movie stars Sean Penn, Tim Robbins and Kevin Bacon as three childhood friends who are driven apart by one tragedy and pulled into each other’s orbits by another years later.

Jimmy Marcus (Penn), Dave Boyle (Robbins) and Sean Devine (Bacon) live in a working-class town divided into the Flats, for those at the lower end of the chain, and the Point, for higher-level employees. Their relationship is as fragmented as their neighbourhood. The cracks become most evident when Dave is abducted by two men posing as police officers. While Dave escapes from his kidnappers’ clutches, he loses a part of himself, and his friendships, to the tragedy.

The three go on to lead vastly different lives. Jimmy becomes a local gang leader of sorts but decides to “go straight” for his daughter’s sake, Sean becomes a police officer and Dave ambles through a life of mediocrity, struggling to reconcile his external world with his inner angst.

Decades later, when Jimmy’s 19-year-old daughter is brutally murdered, Sean is assigned the investigating officer in the case. The same night that Katie is killed, Dave comes home with blood on his hands. As their lives intersect once again, the old tragedy continues to leave its mark.

Mystic River (2003).

Mystic River is centred on a murder, but Lehane’s novel is much more than a mystery. Filled with morbid insight into the workings of the world, it has the makings of a tragedy.

Serendipity works in inverse in Mystic River – two seemingly disconnected events seem to influence each other in unfortunate ways. Lehane suggests that Dave’s kidnapping set in motion a series of events that culminate in Katie’s murder. When Dave was abducted, Sean and Jimmy were also present. The fake policemen rounded the three of them up on a flimsy pretense, but asked only Dave to get into the car. Sean and Jimmy neither came along nor stopped Dave – as adolescents, they knew no better.

The hidden link between that betrayal and the tragedy that befalls Jimmy’s family is articulated by the grieving father at the police station after Katie’s body is discovered. “You ever think how the most minor decisions can change the entire direction of your life?” Jimmy asks. “…Say you and me, Sean, say we got in that car with Dave would have been a very different thing.” Jimmy then goes on to conclude that had they shared that tragic experience with Dave, Katie would never have been born and would hence never have been murdered.

What Sean dismisses as the curious musings of a grieving man prove to be a motif of sorts in Mystic River, for old sorrows continue to inform new wounds in the novel.

Mystic River (2003).

These themes are retained in Eastwood’s film adaptation, which, for the most part, does not veer from Lehane’s course. Screenwriter Brian Helgeland retains much of the author’s powerful dialogue, and the actors are well suited to their parts – Penn and Robbins won Academy Awards for their performances.

The movie mirrors the brooding tone of Lehane’s novel. This is not a archetypal thriller with rapid cuts and edge-of-seat action. It’s a mystery that unfolds gradually, every scene tinted with the darkness of the world in which it it set.

But the wisdom of the book is stripped down on the screen. To accommodate Lehane’s 450-plus pages into a 138-minute run-time, Eastwood has to filter out all that is not germane to the plot. However, the slow-burn of the literary source allows Lehane to explore the characters in detail, which is crucial to a book where the external action is as significant as the characters’ psychological explorations.

While the film takes us to the discovery of Katie’s body in the first 30 minutes, Lehane’s novel brings readers to that conclusion after a hundred pages of agonising over her fate, the build-up giving the author a chance to evocatively describe the backdrop against which this crime unfolds.

The biggest casualty of this brevity are the female characters of Mystic River, who are missing from much of the action. Included in the book largely as wives and mothers, only their thoughts give readers access to their depths. For the most part, they stay on the sidelines, influencing outcomes in pivotal but hidden ways.

Annabelle, Jimmy’s wife and Katie’s stepmother, is “one tough goddamned woman”, according to the book. We see but a glimpse of that in one of the final scenes of the film, in the character played by Laura Linney.

Celeste, Dave’s wife, is more indecipherable, both a victim of her circumstances and a catalyst in the plot. In the movie, her character, played by Marcia Gay Harden, gets short shrift. A paper titled Beneath the Surface: An Examination of Masculinity and Femininity in Dennis Lehane’s Mystic River argues that the author, while depicting sexist gender norms and patriarchal structures in his novel, also covertly undercuts these, especially through Annabeth and Dave’s characters. That nuance, if it does exist in the book, is missing from the film.

Mystic River the movie works well as a mystery-drama with a tragic undertone. As a book, Lehane’s Mystic River is a tragic exploration of the human condition first, and a murder mystery second.

Mystic River (2003).