Butcher Block is a weekly series celebrating horror’s most extreme films and the minds behind them. Dedicated to graphic gore and splatter, each week will explore the dark, the disturbed, and the depraved in horror, and the blood and guts involved. For the films that use special effects of gore as an art form, and the fans that revel in the carnage, this series is for you.

Movies have a long-standing relationship with serial killers, from larger-than-life fictional personalities like Patrick Bateman and Hannibal Lecter to true-crime enigmatic killers like Charles Manson and Ted Bundy; it’s as though there’s an inherent need to delve into the pathology behind these twisted minds in film. Henry: Portrait of a Serial Killer exists far removed from the rest; based on real-life serial killer Henry Lee Lucas, this horror film isn’t interested in the whys of its killer. Instead, it’s a voyeuristic window into his life, one so uncomfortable that the film sent the MPAA into a tizzy and wound up on the shelf for years until finally getting a release.

Co-writer/director John McNaughton’s feature debut, Henry doesn’t really have a story in the traditional sense. It opens to a shocking frame of a discarded dead woman, completely naked and covered in blood, before cutting to Henry (Michael Rooker), a seemingly normal man going through a mundane daily routine. As he quietly eats his breakfast before driving on through town, the film continues to juxtapose these ordinary moments with brutal shots of the dead bodies that Henry is leaving in his wake. It’s a chilling introduction to the casual, impulsive nature of Henry. This matter-of-fact style of slaying, combined with McNaughton’s choice to film in 16mm, gives Henry an overall gritty feel that seeks to drive home that the world’s scariest monsters have no motive behind their actions.

Henry shares an apartment with his former jail mate Otis (Tom Towles), who just picked up his younger sister Becky (Tracy Arnold) from the airport to stay with him for a while. Becky is the closest thing the film has to an audience proxy, a vulnerable young woman with a long history of sexual abuse who’s currently fleeing an abusive relationship. It’s through her that we learn a little more about Henry’s past, and it’s through her that we’re given just a smidgen of hope that there’s some kind of logic to Henry’s homicides. When Becky pries about Henry’s murder of his own mother, he can’t even get the details right. It’s a major red flag that hints at how many murders he’s committed, but also how very insignificant the act of murdering is to him. Becky’s too broken to notice; she instead relays her own traumatic past.

Once Otis embarks on a killing spree with Henry, McNaughton continues to ratchet up the tension, dread, and unease the more the pair gleefully approach their ruthless deeds with reckless abandon. It culminates in one harrowing doozy of a finale, and McNaughton brilliantly brings things full circle by having the film’s final victim unwittingly admire the guitar that belonged to one of Henry’s earliest victims, a hitchhiker.

The MPAA famously said that no number of edits would pass Henry: Portrait of a Serial Killer with an R-rating. It’s a revealing statement considering how very little gore there is throughout the film, save for a couple of effective death sequences and cutaways to the bloody aftermath. When the film finally saw release a few years after its premiere at the Chicago International Film Festival, unrated no less, the reception was polarizing.

McNaughton delivered an unflinching portrayal of what a serial killer really looked like, saturated in realism and completely devoid of the entertainment value that usually sugarcoats the most depraved aspects of humanity. For some, being put into the voyeuristic role of watching Henry commit his heinous acts in all its ugliness was too much to handle. Brilliant direction and an uncanny performance by Rooker make Henry: Portrait of a Serial Killer one of the most distressing, terrifying horror films of all time.

Sometimes it’s not gore that disturbs, but uncomfortable truths.