After the execution of a motorcycle gang leader convicted of murder, a helmeted biker goes on a killing spree during spring break in Florida.
In Miami, the leader of the Demons motorcycle gang, Diablo, is sentenced to the electric chair. Before being executed, he says that he is innocent and was framed by the Chief of Police Strycher in the murder of a young woman. He promises to return from beyond to seek revenge. In the Easter Holliday, the city is crowded by young people when a biker gives a ride to a young woman and electrocutes her on the road. Meanwhile, the body of Diablo is missing in his grave and the Mayor Loomis, Doc Willet, Strycher and Rev. Bates believe his gang has stolen his coffin. When the corpse of the young woman is found, they decide to cover up the information to the press. The football players and friends Skip and Ronny come to the city to forget the defeat in their last game and have a good time. They meet the bartender Gail and soon Ronny gets in trouble with the Demons gang. They beat him and immediately after, he is burned by the mysterious biker. However, Loomis and Strycher press Doc Willet to vanish with Ronny's body. When Skip decides to look for his friend, he finds a ring of corruption in the city while the mysterious biker proceeds his crime spree.—Claudio Carvalho, Rio de Janeiro, Brazil
At dusk, a number of bikers are standing together outside a prison as if in mourning. Inside, Diablo, a prisoner, is led down "the mile" for his execution. When strapped in the electric chair, Diablo screams and curses at the guards, in particular the police officer, Strycker. Before he is executed, the prison warden asks if he has any last words or make a last statement. Diablo says: "I've been framed, but I'll come back to get even!" The switch is thrown.
A few days later, a local policeman says: "welcome to spring break, the annual migration of the idiot". Thousands of college students are flocking up and down the Florida east coast for their week of spring vacation, settling in on Fort Lauderdale. Two teenage boys, Skip and Ronnie, are checking into a small hotel where Skip is recognized by the hotel desk clerk as the quarterback who threw an interception at the Orange Bowl.
Meanwhile, the cops learn that Diablo's body has been taken from the cemetery. Reverend Bates, who was present at the execution, is at the cemetery, and he reminds everyone of Diablo's last words. That night, a girl is hitchhiking, and a biker clad in black leather stops. She asks the biker if he is going to Manatee Beach for spring break, and he slowly nodes his head. After driving at a breakneck speed, the girl complains. The biker stops and lets her off, and then electrocutes her to death with a system attached to the motorcycle.
The next day, Skip and Ronnie almost get into a scuffle with the Demons, the motorcycle gang whom Diablo was the leader, outside a local bar. Officer Strycher shows up and stops the Demons from doing anything, and the boys go inside the bar. Skip meets Gail, the bartender, who was seen in the opening scene at Diablo's execution. Skip does not seem to be into the bar scene, and Gail seems impressed by the football player. Skip also turns down a date with Rachael, the Reverend Bates' daughter. Ronnie is later picked up by Trina, a lady biker of the Demons. She leads him into an alley where the Demons proceed to beat him up and rob him. After the Demons leave the scene, the mysterious helmeted, black-leather-clad biker shows up when Ronnie is able to stand up. Ronnie takes a swing at him, steadies himself with the motorcycle, and is electrocuted and incinerated.
When the mayor of Fort Lauderdale hears about this latest killing, he wants to cover up Ronnie's murder so that no one will suspect a serial killer. While looking for his friend, Skip spots Trina wearing a football medal similar to the one Ronnie had. She tells Skip that she got it from her "old man", but Skip, who does not believe her, follows Trina to the Demons hide out. Skip is spotted and captured and when the Demons prepare Skip for another brutal beating, Strycher arrives with a warrant; he is looking for Diablo's body.
Back at the hotel, a voyeuristic clerk is murdered while peeping through a small hole in the wall of a closet. Kimberly, a student having sex with an older man and providing him with sad stories about her parents lost business (in order to exact pity/pleasure compensation), sees the peephole and an eye looking through it. After sending the man on his way, Kimberly runs to check the closet and finds the dead man. Before she can escape in the elevator, the killer murders her.
Gail goes with Skip, first to the hospital for his injuries, and then to the police station to report Ronnie's disappearance. Later, Skip waits for Dr. Willet in the doctor's car and demands to know where his friend is. Dr. Willett tells him where Ronnie is buried. Skip travels to the cemetery where Strycher finds Skip, threatens him and orders him to leave town.
Meanwhile, Dawg (the Demon's new leader since Diablo's demise) is arrested for the hotel murders. At the same time, Skip hides out at Gail's place where he tells her that someone might have killed Ronnie. Together, they catch Trina alone and she tells him she does not know who killed Ronnie, and that Diablo did not kill Gail's sister Mary (the murder for which Diablo was blamed and executed for). Earlier, Diablo's innocence was verified by Strycher, who told the mayor, "you wanted a patsy," in reference to Mary's death. Skip and Gail suspect that Officer Strycher to be the one responsible for the killings. They sneak into his place and find photographs of the dead girls.
That evening, the Demons bust Dawg from the county jail. When Skip and has a run-in with Strycher, the Demons show up. Dawg shoots Strycher, and the bikers drag the wounded officer around on a chain until he is dead. Gail finds Diablo's corpse at the gang's hideout and soon the murderer arrives where he reveals himself to be Reverend Bates, who tells Gail that he has been killing people whom he believes are sinners (and admits to the murder of Mary). Skip shows up in Strycher's car, and he and Gail try to escape from the reverend. Bates chases after him, but wrecks his motorcycle and is electrocuted by power wires.
