On the way to the city, Mari and Phyllis hear a radio report of a recent prison break, involving violent criminals by the names of Krug Stillo (David Hess), his son Junior, Sadie (Jeramie Rain) and Fred "Weasel" Podowski (Fred J. Lincoln). Upon arrival in the city, Mari and Phyllis stroll the streets, seeking someone who might sell marijuana. Eventually, they run into Junior, who leads them back to an apartment, where they are immediately entrapped by the criminals. Phyllis, who resists, is punched in the stomach and raped, as Mari watches in horror. Mari's parents, meanwhile, prepare a surprise party for her.
The next morning, the girls are locked in a car trunk and driven to the countryside as the gang intends to leave the state. The villains' vehicle breaks down, though. Unable to get their car fixed, they drag the kidnapped girls into the woods. Removed from the trunk, Phyllis is beaten after biting Krug's hand; meanwhile, Mari, bound and gagged, realizes that they are coincidentally right near her own home. As she is helplessly dragged to the woods, her parents sit inside with two bumbling local police officers who assure them that Mari is probably fine. The officers disregard the gang's broken-down car when driving back to the police station.
In the woods, the girls are untied and subjected to several tortures, including forced urination, exhibitionism, and molestation at the hands of Krug's girlfriend, Sadie. At the police station, the bumbling police officers realize their mistake in disregarding the car near the Collingwood's home and quickly set out. Their car breaks down en route, however, and the cops unsuccessfully try to hitch a ride with a group of hippies and a chicken farmer.
After Phyllis and Mari are forced to have sex, Sadie molests Mari. Phyllis whispers to Mari she will make a break for it to distract the kidnappers and thus, offer Mari an opportunity to escape. Phyllis takes off, chased by Sadie and Weasel, while Junior stays behind to guard Mari, who makes a desperate attempt to convince the troubled addict that he doesn't need to listen to his abusive father because Dr. Collingwood, her father, can help him instead. She also gives him her peace symbol necklace as a symbol of her trust. Meanwhile, Phyllis is eventually cornered at a cemetery, where Weasel stabs her in the back. The defeated Phyllis attempts to crawl away, but the gang inevitably catches up with her and repeatedly stab and disembowel her.
Mari eventually convinces Junior to let her go, though their timing is too late, as they are immediately halted by Krug. He presents Phyllis' severed hand and proceeds to carve his name into Mari's chest before sexually violating her. Following this act, Mari, sick from shock and blood loss, rises and slowly staggers over to the nearby lake. Krug shoots Mari in the head and she drifts away. Krug, Junior, Sadie and Weasel wash up and change out of their bloody clothes.
In their new attire, the gang shows up at the Collingwood's home, masquerading as traveling salesmen. Mari's parents agree to let them stay overnight. However, Junior exposes their identity, when his withdrawal symptoms cause him to end up vomiting in the bathroom, where Mari's mother Estelle sees Mari's peace symbol necklace dangling around his neck. She and Dr. Collingwood rush out into the woods, where the couple finds Mari's body by the lake. They decipher that their house guests killed their daughter.
Inside the house, Dr. Collingwood carries his shotgun into his daughter's bedroom, where two of the criminals are sleeping. Krug escapes into the living room and overpowers the doctor, but the criminal is then confronted by his own son, who now brandishes a firearm. Junior threatens to kill his father. However, Krug psychologically manipulates the already troubled young man, and Junior commits suicide with the weapon. As soon as Krug notices that Dr. Collingwood is missing, the doctor attacks Krug with a chainsaw.
Outside, Estelle has duped Weasel into a sex game, which concludes with her biting off the criminal's genitals. Weasel collapses in agony. Meanwhile, Dr. Collingwood continues approaching Krug with the chainsaw, as the sheriff arrives and pleads with the doctor not to go through with it. Dr. Collingwood murders Krug with the chainsaw anyway. Sadie runs outside, where she trips and drops her weapon. Estelle tackles Sadie, and after a struggle, Sadie punches Estelle but trips once again and falls into the family's pool. Estelle catches up with Sadie and slits her throat. The couple reunites in their living room in their blood-spattered clothes as the police look at the family and their murdered guests.
The Craven film was controversial for its graphic violence, and for the manner in which the villains imposed their psychopathic and sadistic will upon the victims. Craven was highly influenced by news Vietnam War footage and wanted to convey that sense of violence he saw in that footage.
The film split opinion with critics, unsure whether the film is a bold artistic statement or exploitative trash, or some combination of the two. Audiences, however, flocked to see the film and, along with films such as The Texas Chain Saw Massacre, it is credited with bringing a new sense of realistic violence to the modern horror film genre.
Film critic Roger Ebert named the film one of his "Guilty Pleasures", and noted that the story closely follows that of Ingmar Bergman's classic film The Virgin Spring (1960), an Oscar winner for best foreign language film. Ebert called The Last House on the Left "a neglected American horror exploitation masterpiece on a par with Night of the Living Dead.
Wes Craven has since directed many popular horror films including The Hills Have Eyes, A Nightmare on Elm Street, and Scream. Producer Sean S. Cunningham, meanwhile, went on to initiate one of the biggest horror film franchises in the 1980s with Friday the 13th.
The film was originally shot with Mari's parents finding her still alive, identifying her attackers before she dies. Editing and dialogue changes were made to depict Mari as dead when her parents find her. However, in the film when her parents find her, she can be seen moving and breathing, and her parents mouths don't match the dubbed "She's already dead" dialogue.
Although the soundtrack was released commercially around the same time as the film, it did not sell very well, although it has recently become available via David Hess' website.
The film remained banned throughout the remainder of the 1980s and into the 1990s. However it had built a cult reputation in the UK, plus critics such as Mark Kermode began to laud the film as an important piece of work. In 2000, the film was again presented to the BBFC for certification and it was again refused, though it was granted a license for a one-off showing in Leicester in June 2000, after which the BBFC again declared that the film would not receive any form of certification.
In June 2002 the BBFC won against an appeal made to the Video Appeals Committee by video distributor Blue Underground Limited. The BBFC had required 16 seconds of cuts to scenes of sexual violence before the video could be given an ‘18’ certificate. Blue Underground Limited refused to make the cuts, and the BBFC therefore rejected the video. The distributor then appealed to the VAC, who upheld the BBFC's decision. During the appeal, film critic Mark Kermode was called in as a horror expert to make a case for the film's historical importance. However, after his report, the committee not only upheld the cuts but doubled them.
The film was eventually given an 18 certificate with 31 seconds of cuts on the 17th July 2002 and was released in the UK on DVD in May 2003. The cut scenes were viewable as a slideshow extra on the disc, and there was a weblink to a website where the cut scenes could be viewed.
The BBFC classified the film uncut for video release on the 17th March 2008.