Tobe Hooper once said “I don’t believe in using too much graphic violence, although I’ve done it. It’s better to be suggestive and to allow the viewer to fill in the blanks with their minds.” The Texas Chainsaw Massacre (1974) is not one of the finest horror experiences ever put to film because of on-screen slaughter, but rather the suggestion of bloodshed. The long-lasting effect of Hooper’s direction was borne from the simple presentation of a scenario, the resulting (and very personal) nightmares were conjured entirely within the headspace of whomever laid eyes on it.

The concept isn’t exclusive to TCM, but certainly applies to John McNaughton’s tense tale of a week in the life of a sociopath, 1986’s Henry: Portrait of a Serial Killer. Though it made its way around film festivals for years, the Motion Picture Association of America’s inability, or unwillingness to give it a straight R-rating delayed its limited theatrical release for 4 years.

As legendary film critic Roger Ebert noted, however, “This film deserves to be seen,” and over the course of more than three decades, it has become essential viewing for horror aficionados everywhere. And not for overt violence, although like Hooper, it had its fair share, but rather for what wasn’t seen.

Make no mistake, the reasons for suggestion in this case were partially due to budgetary and time constraints. However, McNaughton wanted to truly explore the inner workings of Henry’s (Michael Rooker) mind, as well as his relationship with Otis (Tom Towles) and Becky (Tracy Arnold), which meant that on-screen violence would have to be dispersed carefully, but to offer a true glimpse at the danger housed within the protagonist, the film would need to be littered with other misdeeds.

And that is where the power of suggestion entered the equation, in part through the utilization of brilliant music cues strewn throughout by film editor Elena Maganini. Portrait of a Serial Killer’s main theme is composed of the simplistic yet powerful piano chords of Ken Hale, Steven A. Jones and Robert McNaugton that matched Rooker’s icy glare, begging the question, what truly resided beneath the surface.

The horrors left in Henry’s wake were revealed through a series of pan shots, offering a peek behind a veneer that should never come into focus. Again, the issues of budget and time factored into McNaughton’s decision-making, yes, but ultimately the road followed was that which would make the greatest impact, and that avenue was paved by sound editor Cory Coken and post-production sound mixer Ric Coken. The audible screams of victims blended with Henry’s angry commands to “shup up!” underneath ghastly visuals painted a picture that turned blood cold, as viewers were burdened with whatever terror played before their mind’s eye thanks to the macabre melody dancing through their heads.

All which set up McNaughton’s final stroke of genius.

After Henry returned to the apartment to find Otis raping his sister, and the ensuing scuffle that resulted in Otis’ death, Henry’s instinct took over and he dismembered his friend’s body in the bathtub before hitting the road with Becky.

In a wink to the audience, another music cue foretold Becky’s fate, as “Loving you was my mistake” sprang from the radio before the pair reached their roadside motel.

The following morning, pulling to the side of a desolate road in the middle of nowhere, Henry exited his vehicle and waited for cars to pass before he opened the trunk. When it had reached its apex, it was accompanied with a single, ominous piano chord. To that point, there may have been hope that Becky had already been in the car when the vehicle pulled away from the motel, but in that moment, the audience knew.

Henry waited for another car to pass, then glanced over his shoulder to ensure no others were coming, lifted Becky’s blue suitcase, now her tomb, and laid it at the top of a ditch beside his car. Once again, the terrified shrieks of one of Henry’s victims echoed as the luggage connected with the earth below. McNaughton had cinematographer Charlie Lieberman hold the shot, and slowly zoom to the blood-smeared bag, a grotesque exclamation point on a film that has always carried an unsettling tinge of documentary.

As Henry pulled away and the camera closed in, all that was left were the curdling chords of Henry’s theme, and the remains of the one person it appeared Henry may have had the slightest sentiment for. Uncaptured and unpunished, the sounds perfectly encapsulated the unknown of where Henry, or those like him—who unquestionably exist—would head next.

The visceral images of McNaughton’s masterpiece proved too much for many audience members to endure when it first reared its head at film festivals decades ago, and abandoned it to what Ebert described as “the purgatory between [an] R and X [rating].” The film was too powerful and too well done to be contained for long, but for the violence we witnessed, including the devastatingly difficult to digest home invasion segment, it was the intonations left unseen that made Portrait of a Serial Killer so indelible.

They were haunting in 1986, and haunting today.