Mae Coleman and Jack Perry are an unmarried couple living together (in the jargon of the era, they are "living in sin") and selling marijuana. Mae prefers to sell marijuana to customers her own age, whereas Jack sells the plant to young teenagers. Ralph Wiley, a psychotic ex-college student turned fellow dealer (and addict, according to the film), and Blanche help Jack sell cannabis to students. Young students Bill Harper and Jimmy Lane are invited to Mae and Jack's apartment by Blanche and Ralph. Jimmy takes Bill to the party. There, Jack runs out of reefer. Jimmy, who has a car, drives him to pick up some more. Arriving at Jack's boss' "headquarters," he gets out and Jimmy asks him for a cigarette. Jack gives him a joint. Later, when Jack comes back down and gets into the car, Jimmy drives off dangerously, along the way running over a pedestrian with his car. A few days later, Jack tells Jimmy that the pedestrian died of his injuries. Jack agrees to keep Jimmy's name out of the case, providing he agrees to "forget he was ever in Mae's apartment". Jimmy does indeed escape the consequences of his crimeâa rare occurrence in the film.Ralph is arrested for Jack's murder.Bill begins an affair with Blanche. Mary, Jimmy's sister and Bill's girlfriend, goes to Mae's apartment looking for Jimmy and accepts a joint from Ralph, thinking it to be a normal cigarette. When she refuses Ralph's advances, he tries to rape her. Bill comes out of the bedroom after having sex with Blanche and hallucinates that Mary strips for Ralph. He attacks Ralph. As the two are fighting, Jack tries to break it up by hitting Bill with the butt of his gun. The gun goes off and Mary is fatally shot. Jack puts the gun in the hand of an unconscious Bill and wakes him up. Bill sees the gun in his hand and is led to believe that he has killed Mary. The group of dealers lies low for a while in Blanche's apartment while Bill's trial takes place. Ralph, losing his sanity, wants to tell the police who is actually responsible for Mary's death. The film attributes Ralph's insanity to marijuana use.Seeking advice from his boss, Jack is told to shoot Ralph so he keeps his mouth shut. Meanwhile, at the apartment, Blanche offers to play some piano music for Ralph to keep his mind off things. They are both very high and Ralph tells her to play faster. She increases her playing speed to a downright cartoon-like speed in one of the film's most famous and over-the-top sequences.[9] Jack shows up and Ralph immediately senses that Jack wants to kill him so he beats Jack to death. The police arrest Ralph, Mae and Blanche. Mae talks and the criminal gang is rounded up. Blanche explains that Bill was innocent and he is released. Blanche is then held as a material witness for the case against Ralph but rather than testify against him, she jumps out a window and falls to her death. Ralph is put in an asylum for the criminally insane "for the rest of his natural life." Mae's ultimate fate is unspecified.The film's story is told in bracketing sequences at a lecture given at a PTA meeting by the high school principal, Dr. Alfred Carroll. At the end of the film, he tells the parents he has been talking to that events similar to those he has described are likely to happen again and then points to random parents in the audience and warns that "the next tragedy may be that of your daughter ... or your son ... or yours or yours ..." before pointing straight at the camera and saying emphatically "... or YOURS!" as the words "TELL YOUR CHILDREN" appear on the screen.
Output: Question: WHAT DOES HE WARN THE PARENTS?, Answer: THE NEXT TRAGEDY MAY BE THAT OF YOUR DAUGHTER... SON ...