We’re about a half-century into the ongoing popularity of the slasher genre. For most of that time, the colorful killer is paradoxically the protagonist of the piece … or at least the most marketable aspect of it. There are always scares to be had in stories about spree killings. We get a few deconstructions, maybe a meta-textual story (the Scream films) or even some throwback takes on the genre (Halloween Kills) every year. The Toolbox Murders, from 1978, is a grimy piece of work that remains more upsetting than anything I’ve seen over the past few years. It tracks that the new 4K restoration is set for release by Blue Underground, the boutique label founded by William Lustig, director of Maniac — perhaps the only film Toolbox compares to in skin-crawling depravity.

That’s a lofty statement, of course. Audiences in the 21st century can see far more graphic depictions of gore and death on cable television. They can live out psychopathic fantasies in all manner of entertainment. True-crime podcasts that explicitly detail real-life murders continue to be one of the most popular forms of broadcast media (albeit very much not for me). There’s nothing like a movie, though, a creatively curated sensory experience of murder and foul behavior.

Toolbox was banned from Britain in the 1980s. Critics called it misogynistic.

Well, sure.

The story opens with a series of brutal murders by a ski-masked man who stalks several women living in a Los Angeles apartment complex. He invades their homes, armed with a toolbox filled with everyday instruments of death. A hammer, a screwdriver and, famously, a nail gun. That last implement is utilized during an iconic scene that opens with Dee Ann DeVore (Kelly Nichols) masturbating in a bathtub while “Pretty Lady” by George Deaton and Terry Stubbs plays in the background. She reaches climax, opens her eyes and sees her voyeur. It’s a nightmare moment of pure exploitative filmmaking. Why does she wear dark red lipstick and earrings to the bath? Because it makes for a great scene.

It’s not all murders and overt sexuality, though. After his spree, the killer kidnaps Laurie Ballard (Pamelyn Ferdin), a 15 year-old girl. What he wants with her, and whether the police and her brother, Joey (Nicholas Beauvy) can find her in time, is the primary plot of the film. The middle isn’t as exciting, but the ending is an avalanche of evil works and bad energy. Screams are rarely used so effectively these days.

The new UHD disc offers a glorious grindhouse visual experience. The colors, the grit of the film-stock and the odd and low-budget technical work all enhance the sense that maybe, just maybe, we weren’t meant to watch something this bleak and cruel. As one of the most infamous “video nasties” of its era, there’s nothing better than maintaining that forbidden feeling.

Extras include a new audio commentary with film historians Troy Howarth and Nathaniel Thompson, a new interview with director Dennis Donnelly, a new interview with co-star Wesley Eure and a new interview with Nichols. Additionally, Blue Underground commissioned a new feature in remembrance of actor Cameron Mitchell and a new video essay by film historians Amanda Reyes and filmmaker Chris O’Neill.

One of Blue Underground’s goals in releasing new restorations of films like The Toolbox Murders is, frankly, giving underground films with historical significance their due. This one is unforgettable, and the special features do a great job giving it the context modern audiences might seek for how The Toolbox Murders became so influential on the slasher films we watch today. This is a great release.