Despite not being a commercial success when released, the film received positive reviews, with many praising the atmosphere and cinematography. The film has gained a cult following over the years.
Two men named Ty (Mike Kellin) and Vachel (Charles Bartlett) are hunting in a forest and come across an abandoned church, which they go in to explore. After Ty sees their truck being crashed into a tree, Vachel is stabbed with a serrated machete by a chuckling assailant who then dons Vachel's hat and jacket. Ty, seeing the murderer come out of the church, quietly flees off into the forest. Meanwhile, forest ranger Roy McLean (George Kennedy) is at his home, where he encounters a van of five college-aged adults heading to rural property which one of them has inherited. Despite his insistence that they not venture up the mountain, the five continue along. Among them are Warren (Gregg Henry); his girlfriend Constance (Deborah Benson); Jonathan (Chris Lemmon), and his girlfriend, Megan (Jamie Rose); and Daniel, Jonathan's brother (Ralph Seymour).
On their way up the mountain, they hit a deer, and encounter Ty stumbling through the woods on his way down the mountain; they dismiss his warnings of "demons," as he is visibly drunk. After reaching a point where the van cannot drive any further, the group set out and foot and make a campsite; at night, while around the fire, Constance, Megan, and Daniel hear noises around them and become frightened, only to find that Jonathan and Warren are playing a joke on them. The next morning, they hike along Silver Creek to a waterfall, where they see a young girl named Merry Cat Logan (Kati Powell) singing before noticing their presence and running into the woods. Megan and Jonathan go skinny dipping at the bottom of the falls, unaware that someone else has entered the water. Megan feels hands touching her and assumes it's Jonathan, until she sees him on shore, whereupon she panics and swims to safety.
When the group splits up to go exploring, Jonathan spots Merry and chases after her. She runs to a clearing but sees something that frightens her and hides behind some trees. Jonathan assumes it's the rope bridge over the waterfall ahead and begins to go across, only to be confronted by the killer, who cuts his hand with his machete. The killer severs the bridge and Jonathan plummets into the water below. Unable to swim, he attempts to climb back up over the ledge using the rope. When he reaches the ledge, the killer kicks him in the face, and he falls to his demise. Meanwhile, Megan and Daniel are taking photographs in the woods, and come across the church and a graveyard. Daniel, who has lost his glasses, sees a figure coming through the woods, and thinks it's Jonathan. He and Megan pretend to kiss as a joke, but as the figure comes closer, Daniel realizes it is not his brother. The figure stabs Daniel, and Megan flees into the church, where she watches through the window as the killer investigates Daniel's camera. Suddenly, another identical man emerges behind her inside the church, realizing that the two are identical twins; she is murdered in the church while the other twin photographs her death from outside the window.
Warren and Constance (now barefoot and in shorts) return to the camp, but cannot find anyone else. While wading through the river, they encounter Jonathan's body floating downstream, and pull him out. As night approaches, Warren leaves Constance at the campsite to retrieve the car keys from Jonathan's body, but it's not where he left it; nearby, he finds Jonathan's body against a tree. Meanwhile, Ty finally encounters Roy in the woods and tells him about the twins at the church. Roy goes out on his horse to find the teens, and comes across Merry's family. They tell him that the twins were actually their own and their mother died during childbirth, so he mated with his daughter and had Merry. Left alone, Constance is attacked by one of the twins, who chases her up a tree. The twin cuts down the tree, and just before he is about to kill Constance, Roy shoots him and he tells the couple to go pack their items. They go back to camp, as Merry runs through the woods to find them. At camp, the other twin stabs Warren and tries to kill Constance, who rams her fist down his throat, choking him to death. Warren begins to sob and Merry watches from the trees, as the sun rises in the forest.George Kennedy as Roy McLean
Mike Kellin as Ty
Chris Lemmon as Jonathan
Gregg Henry as Warren
Deborah Benson as Constance "Connie"
Ralph Seymour as Daniel
Katie Powell as Merry Cat Logan
John Hunsaker as Mountain Twins
Charles Bartlett as Vachel
Jamie Rose as Megan
Hap Oslund as Pa Logan
Barbara Spencer as Ma Logan
The film's original script, based on a story by Joseph Middleton, was titled The Tennessee Mountain Murders, and later The Last Ritual, and had heavy religious themes behind the twin killers' motives, which director Jeff Lieberman felt were awful. It also included a sixth camper named Eileen and a different fate for Megan, which entailed her being tossed to her death over a cliff. It also included a climax involving Connie being forced to handle rattlesnakes by the inbred villains before becoming one of their wives; this version of the script also had more involvement from the Logan family, who were part of the scheme. Lieberman rigorously rewrote the screenplay from page one by himself to eliminate all the religious overtones in favor of a more thriller-based plot. Lieberman was heavily influenced by Deliverance (1972) while writing the film.
The film was shot on location in the spring of 1980 at the Silver Falls State Park in Sublimity, Oregon, just outside nearby Salem, and an hour away from Portland, Oregon. Due to the film's low budget, filming time ranged from 14-15 hours per day. The 1980 eruption of Mt. St. Helens occurred during filming; according to actor Chris Lemmon, he and the rest of the cast were gone for the day on a trip to the Oregon coast when the eruption occurred.
Despite its authentic, weathered appearance, the church used in the film was actually built for the production. Director Jeff Lieberman said that countless strangers showed up at the filming location on the day that the scene with Jamie Rose swimming topless was to be filmed. Lieberman said that word of this shoot had apparently gotten out among the local forest rangers.
Several odd occurrences happened during the shooting of the film; particularly, while shooting in the woods one evening, the lighting went out without explanation, leaving the cast and crew in complete darkness. After several minutes the producer yelled out 'let there be light!', and the lights immediately returned without explanation. According to director Lieberman, despite the numerous reviews of Just Before Dawn that implied it was inspired by The Texas Chain Saw Massacre (1974) or The Hills Have Eyes (1977), he had not seen either film at the time of making Just Before Dawn. Lieberman also stated that he was influenced by Ingmar Bergman when assembling some of the film's compositions.
The eerie whistling motif heard in Brad Fiedel's music score is a reference to the rescue whistle that Warren carries in the film. According to Fiedel, many of the ominous sounds in the music score were actually electronically altered audio clips of himself vocalizing droning noises.
Initially, Universal Pictures expressed serious interest in purchasing the film but eventually backed out. Instead, the film was distributed by Picturmedia, a small independent company. Just Before Dawn was released theatrically in October 1981 in the United States. It debuted the following month in France, where it was released under the title "Survivance," as if to emphasize a connection with John Boorman's Deliverance.
AllMovie's review of the film was favorable, writing, "Anyone lucky enough to fish out a copy of director Jeff Lieberman's Just Before Dawn will certainly find themselves richly rewarded."
Just Before Dawn was released on DVD on July 26, 2005 from Media Blasters, in a 2-disc special edition, and features a director commentary as well as a documentary on the making of the film. Shriek Show's rights to the film then expired, and it was released on Blu-ray and DVD by Code Red DVD in late 2013. This release is completely uncut, and also features the longer overseas version, with additional dialogue and twelve minutes of additional footage.