There are so many mysteries swirling around the otherwise open-shut courtroom drama “The Whole Truth” that the relatively banal question of who murdered Boone Lassiter is undoubtedly the least interesting. The cops already have their man, and the judge wants a swift trial. Meanwhile, audiences might well ask, what was it that turn-of-the-millennium stars Keanu Reeves and Renée Zellweger saw in this material, which plays like a rejected episode of “Law & Order: SVU”? Or, equally intriguing, why did promising “Frozen River” helmer Courtney Hunt (who spent some of the eight-year span since her impressive indie debut directing episodes of “Law & Order: SVU”) choose to go back to the big screen with such a weak legal procedural?

Reeves plays Richard Ramsay, family lawyer and longtime personal friend to the late Boone Lassiter (Jim Belushi), a rich Southern blowhard found stabbed to death in his bedroom. When the cops arrived at the scene, Boone’s teenage son Mike (Gabriel Basso), by all reports a promising college-bound kid, was kneeling beside the body and said something to the officers that sounded like a confession. Mike hasn’t spoken since, but he’s on trial for the murder, and it’s Richard’s job to get him off, despite what seems like overwhelming evidence to suggest that Mike killed his father.

Already there’s something fishy in this arrangement: If Richard was Boone’s lawyer, and Boone is now dead, should he really be defending the No. 1 suspect? And why, if history has shown that wives are often responsible for such crimes, is no one taking a closer look at Boone’s widow, Loretta (Zellweger), whom evidence suggests may have been the victim of physical abuse and repeated infidelity? Even the camera seems to be avoiding her, at least at first, as Zellweger appears discreetly over Richard’s shoulder, fretfully attending her son’s trial, but getting suspiciously little screen time for someone who surely knows more than she’s letting on. And then there’s the ludicrous detail of Mike’s silence: The young man refuses to utter a word in his own defense, until the last minute, when he suddenly insists on taking the stand — a decision that makes Richard extremely nervous, as the lawyer has no idea what his client might say.

Viewers who’ve spent any time watching TV courtroom dramas will probably believe they’ve figured out “The Whole Truth” from practically its opening scene, and despite a few minor twists along the way, chances are, they have. The real mystery is what this script must have contained that didn’t make it onto the screen, because at a meager 93 minutes, “The Whole Truth” feels like a fraction of some larger, more ambitious project, one in which certain roles — such as the doting mother/long-suffering wife played by Zellweger, or the conflicted young legal aide (Gugu Mbatha-Raw) who joins Richard’s team — surely contributed additional color to this drab-looking drama, whose only energy hails from its agitated piano score. Certainly, the heavy narration by Reeves is a clue to someone’s attempt to simplify and reshuffle things in the editing room.

Whatever the explanation, the resulting film feels like a missed opportunity, one that volunteers the observation that “all witnesses lie” and proceeds to cast in doubt everything that anybody says — a formula by which only the accused, who keeps his mouth shut, seems above suspicion. Meanwhile, Richard has his work cut out for him trying to defend Mike with no help from the young man, and yet, he makes swift progress by painting his late friend Boone as an overbearing monster, using cross-examination to present an image of someone who got what was coming to him.

It’s kind of cheat that the witnesses’ testimony triggers cutaway scenes to Boone’s worst offenses, from picking up loose women on business trips to embarrassing his son in front of neighbors at a family barbecue, considering that those who take the stand offer milder or downright conflicting accounts of the events being depicted. Of course, it’s not really the jury that Richard is trying to convince here, but the audience, for whom Mbatha-Raw’s character serves as proxy — the daughter of Richard’s mentor and a promising young lawyer in her own right. She is perhaps the only truly decent character in this whole mess, though even she has skeletons in her closet. At any rate, much of Richard’s defense has been crafted just for her benefit, and it’s sort of a letdown that she doesn’t play a bigger part when everything starts to unravel.

Looking back to “Frozen River,” Hunt’s long-awaited second feature shares the weaknesses of her debut — namely, a single-minded focus on a somewhat trashy predicament, with little to no room for subplots or other enriching details — while lacking in the earlier film’s strengths. Missing is the gritty suspense and vivid local color, not to mention a central performance as compelling as Melissa Leo’s tooth-and-nail turn. Here, it feels as if anyone could have played these roles, and there’s something a little sad about watching the ever-wooden Reeves and numb-looking Zellweger (convincing as a rich man’s frail, if resourceful wife) settle for such shallow work, considering how much more we know them to be capable of. These two actors were at the top of their game 15 years ago, and though they each comes with certain baggage, truth be told, they deserve better.

Film Review: ‘The Whole Truth’

Reviewed at Real D Screening Room, Beverly Hills, Oct. 5, 2016. MPAA Rating: R. Running time: 93 MIN.

  • Production: A Lionsgate Premiere release of a Lionsgate Premiere, PalmStar Media Capital presentation, in association with Filmnation Entertainment, Merced Finance, of a Likely Story production, in assocation with Atlas Entertainment. Producers: Anthony Bregman, Kevin Frakes, Elon Dershowitz, Raj Brinder Singh. Executive producers: Gideon Tadmor, Eyal Rimmon, Buddy Patrick, Scott Fisher, Jamin O'Brien, Stuart Brown, Vishal Rungta, Nicholas Kazan.
  • Crew: Director: Courtney Hunt. Screenplay: Rafael Jackson. Camera (color): Jules O'Loughlin. Editor: Kate Williams.
  • With: Keanu Reeves, Renée Zellweger, Gugu Mbatha-Raw, Gabriel Basso, Jim Belushi.