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.

Before Wes Craven entered the world of genre filmmaking, he’d been a mild-mannered college professor sheltered in youth thanks to a strict Baptist upbringing. When students asked him to supervise a film they were making, he thought he’d give filmmaking a try as well, and a new passion was born. He moved away from teaching and into film industry thanks to a connection, working as a sound editor at a production company in New York City. It was there that he met producer Sean S. Cunningham (Friday the 13th). The pair worked well together on Craven’s first credit, sex mockumentary Together, giving the business savvy Cunningham the idea to achieve the same level of success with horror. He asked Craven to direct, but I don’t think he (or audiences) were prepared for Craven’s first foray into horror.

For someone who had zero experience with horror movies or directing, Craven delivered one brutal gut-punch of a debut in The Last House on the Left. But Craven did have a lot of experience with repression and forbidden society, having grown up in a household where the only approved films were relegated to Disney. Craven penned a screenplay the drew from The Virgin Spring, which in turn drew from a medieval Swedish ballad, a tragic rape and revenge story. Craven’s approach was pure unflinching confrontation with humanity’s darkest instincts.

The plot follows teen girls Mari Collingwood and Phyllis Stone, off to the city attend a concert for Mari’s 17th birthday, despite reservations from Mari’s parents. Phyllis convinces Mari that they should stop for marijuana on the way, putting the pair directly in the clutches of escaped criminals Krug, Sadie, Junior, and Weasel- all extremely bad news. While Phyllis is gang-raped, Craven contrasts the brutality of it with scenes of the Mari’s parents preparing a surprise party- unaware anything foul has befallen their daughter just yet. Things get far dourer and harrowing for the teens until they’re viciously murdered. It just so happens to be in the woods near the Collingwood’s home, where the gang pass themselves off as salesmen and request to stay the night. When the Mari’s parents put two and two together, their quest for revenge becomes violent and without limit.

Craven never offers a reprieve. Instead of focusing on the rape, he instead makes the viewer complicit in the degradation and humiliation of the film’s victims. When you think Krug and his gang couldn’t be more despicable, Craven pauses to examine their shame- he humanizes them. Conversely, Dr. John and Estelle Collingwood become savage in the latter half; their grief turned to vicious rage. Disembowelments, a bitten off member, amputations, and stabbings, on top of everything else meant that The Last House on the Left was designed to leave viewers feeling repulsed. Violence begets violence, and there’s no happy ending here.

Even though the violence was actually toned down from the original script, the final cut made even Cunningham a bit squeamish; this wasn’t the fun, bloody romp he expected, nor was horror this serious at the time. Those showing up expecting trashy fun were about to get their expectations crushed under a mountain of bleak reality. Be careful what you wish for, here. As more an more theaters picked up the film, Cunningham actually tried to edit out some of the more disturbing sequences to appease the local theaters riled up about the subject matter.

While the film was drawing ire and protests stateside, it was refused a certificate for theatrical release in the U.K. During the era of home video releases a decade later, it caught the attention of the Department of Public Prosecutions under the Video Recordings Act of 1984, and was banned on the Video Nasties list where it remained throughout the ‘90s. It wasn’t until 2008 that the film finally passed completely uncut, though.

The Last House on the Left is the result of a unique pairing between Cunningham and Craven. Cunningham’s strength is his ability to market and sell a film, while Craven challenged the very notion of what a horror film could be. The sadistic nihilism of Craven’s debut meant horror wasn’t just for children anymore. Not all movies are meant to make you feel good. The ‘70s were full of pioneering horror directors delivering graphic, groundbreaking horror, and Craven was among the first. His imprint on the genre loomed large over the decades, but the soft-spoken horror master grabbed horror by the balls from the get go with his gritty debut. But remember; it’s only a movie.