Reptile

Fully inhabiting his role and subtly commanding the screen, Benicio del Toro is the best thing about Reptile, which has the bite of a snake but the pace of a tortoise.

Indeed, this slick and atmospheric murder mystery is best when it’s more about the investigator than the investigation. However, all the melodramatic twists and narrative misdirection can’t disguise the underlying familiarity of the material.

The story is set in New England, where a realtor is brutally murdered inside a house she’s selling. Her boyfriend, Will (Justin Timberlake), finds the body and reports the incident to police.

Del Toro plays homicide detective Tom Nichols, who begins questioning Will about the couple’s relationship issues. Evidence leads him to others who might have clues, such as the deceased woman’s oddball ex-husband (Karl Glusman) or a loner (Michael Pitt) who keeps popping up and apparently has an axe to grind with Will’s family. There’s also Will’s mother (Frances Fisher) and her connections to a mysterious side business, which might take the probe in a new direction.

Employing his unorthodox methods, Tom navigates a parade of creeps and weirdos in which everyone becomes a suspect. While the case eventually takes a psychological toll, especially given the troubles in his recent past, his obsession draws him back in.

As secrets are gradually revealed, the film generates moderate suspense through some intriguing character dynamics, although the feature debut for longtime music-video director Grant Singer doesn’t delve much into its moral complexities or stray from a standard procedural framework.

Del Toro, who is credited as a co-writer along with Singer and Benjamin Brewer (The Trust), brings depth and introspection to a man who’s amusingly eccentric and disarmingly nonchalant, yet also is driven by a detailed and calculated sense of determination.

In fact, the film occasionally pauses the whodunit to focus almost exclusively on what makes him tick — applying texture and sympathy to his relationship with his wife (Alicia Silverstone), his partner (Ato Essandoh), his captain (Eric Bogosian), and others around him.

Meanwhile, the red herrings and cloudy motives might keep you guessing, but will you care enough to do so? As Reptile slithers toward its big reveal, you probably won’t be as invested as its protagonist.

Rated R, 134 minutes.