 In 1996, young Cletus Kasady is talking to his girlfriend, Frances Barrison, through a wall. She is set to be transferred, which devastates them both. She describes her powers getting stronger, and she is worried she cannot control them. Frances is taken away by guards and placed into a truck while Cletus yells for her in vain. In a truck, Frances utilizes her powers against a guard named Mulligan. Her screams produce a supersonic force that incapacitates those around her, and she causes the truck to overturn, but Mulligan fires a shot at her face. Frances wakes up at the Ravencroft Institute, where she is tested by Dr. Pazzo. Jump to the present day at San Quentin Prison where Cletus is insisting that Eddie Brock come to interview him so he can get his story out to the public. Eddie gets called by Mulligan, who is now a detective. Venom wants to eat Mulligan because he's a jerk, but Eddie continues to reign in Venom's hunger for flesh. Eddie meets with Cletus, where he asks Eddie to print a haiku in the paper for him as a message to Frances. Before leaving, Venom tells Eddie to take a closer look into Cletus's cell. Back at the apartment, Venom memorizes the drawings and carvings on the walls in Cletus's cell, which he determines is a clue to where the bodies of his victims are buried. It leads them to a beach, which Eddie reports to the authorities, and sure enough bodies are recovered from that area. This influences the judge and governor to reinstate capital punishment, so Cletus is officially sentenced to death. Venom hasn't been happy lately because Eddie has only been letting him eat live chickens and chocolate. They even have two pet chickens that Venom named Sonny and Cher, which he can't bring himself to eat. He thinks that they should be out there taking out bad guys as the lethal protector. They go to the bodega where Mrs. Chin works, now that she knows about Venom's existence, but she informs them that her chocolate shipment is late. While roaming across the city, the two spot a mugger attacking a woman, so Venom pops out to attempt to snack on the guy, but Eddie manages to talk him out of doing that, to the symbiotes dismay. As they are running across rooftops, they get a call from him, asking Eddie to meet with her. Eddie goes to a restaurant to meet him, where Venom is really hoping that and will take Eddie back. She actually reveals that she and Dan have gotten engaged. Based on Eddie's bodily reactions, and knows that Venom is with Eddie, despite him telling her that Venom died a while back, so she tells Venom to take care of Eddie because he can't take care of himself, and also because he drives other people away. Eddie rides his motorcycle back in dismay, not caring if he gets hurt, but Venom steers him away from danger. Eddie receives a postcard from Cletus, which invites him for one last visit before he is executed. The car also details his past exploits, which include the abuse he suffered at the hands of his father, which led him to killing his grandmother by pushing her down the stairs in her wheelchair, and also electrocuting his mother in the bathtub. Eddie reluctantly visits Cletus, but the madman provokes Eddie by reminding him how he not only drove in a way, but how his father blamed him for causing the death of his own mother during childbirth. This causes Venom to push Cletus against the wall, but when he pulls him closer to Eddie, Cletus bites Eddie's hand and draws blood, although Cletus recognizes that what he is tasting is not ordinary blood. Cletus sees the blood on his finger come alive before ingesting it. Venom notes that he probably just made a huge mistake. Eddie and Venom return home where they have a big argument over Eddie not being able to live his life because of Venom, while the symbiote still complains about his hunger. The two then have a physical fight that includes Venom destroying Eddie's TV before they finally break up, and Venom goes on to possess other unwitting victims. Eddie then proceeds to clean up his apartment. Cletus is set to be executed via lethal injection. However, the symbiote in his blood takes over and sabotages the execution, overtaking Cletus's body and transforming him into carnage. He proceeds to slaughter the guards gruesomely before busting out of San Quentin. He kills another man on the outside and steals his clothes before taking a car to go look for Francis. Carnage tells Cletus that he wants his help in killing Venom so that he will be the strongest symbiote, and Cletus agrees on the condition that he helps him find Francis. They go to a gas station where Cletus kills the clerk and hacks the internet with Carnage's help to learn that Francis is at the Ravencroft Institute. Eddie sees the news about Cletus escaping, and he is immediately visited by Mulligan. Knowing that Cletus took a particular interest in him, Mulligan orders Eddie to keep him updated if he finds out anything about Cletus. Eddie goes to do some investigating based on what Venom picked up and is drawn to St. Estes. He calls Mulligan, who knows it's about Francis, but he believes he killed Francis when he shot her all those years ago. Venom continues going through bodies, but none of them are able to fully contain him before they end up dying. He winds up at a nightclub where people think he is just wearing a really good costume. He delivers an impassioned speech to the people in attendance, who all love him, but he is clearly still missing Eddie. With the current body about to give out, Venom manages to take himself to Mrs. Chen's shop and get her help as he is weakening. Cletus arrives at Ravencroft where Dr. Pazzo is trying to taunt Francis. Soon, Cletus emerges and uses Carnage's tentacles to kill Dr. Pazzo and break Francis from her cell. He renames her shriek for her powers. They then proceed to kill off the guards and then head to St. Estes to burn it to the ground. As authorities an armed personnel approach, Carnage utilizes his abilities once again while Shriek uses her powerful screams against them, but Carnage doesn't like this since the noise weakened symbiotes. He orders Cletus to keep her under control. Eddie is taken into custody by Mulligan for the hope that he can bring Cletus to them. Eddie uses his phone call to contact and to get help. Dan drives her to the station where Eddie explains that he needs Venom to fight back. And then Dan go to Mrs. Chen's shop where he quickly realizes that Venom is using Mrs. Chen as a compatible host and manages to convince Venom to go back with her. They return to the station where he breaks Eddie out. Venom demands a sincere apology from him before returning to his body and Eddie relents and apologizes to Venom for sending him out of his body. Venom then returns to Eddie. Cletus and Shriek plan to have a wedding with the three villains planning to kill their respective targets. Shriek wants Mulligan, Cletus wants Eddie, and Carnage wants Venom. They ambush Mulligan and capture him before going to an and Dan's apartment where Shriek knocks Dan out and then goes to capture him, leaving a note behind for Dan to find. He calls Eddie to let him and Venom know that and is in danger and that the villains want to meet at a cathedral. Eddie, Venom, and Dan arrive at the cathedral for the final showdown. Venom comes in but panics when he sees how big Carnage is. It takes Eddie promising him to allow Venom to eat anybody he wants. Thus begins the epic symbiote battle with Venom fighting Carnage against his many powerful attacks. Shriek tries to help, but Carnage makes her stay out, despite Cletus's protests. Dan manages to hold Carnage down by throwing fire at him. Mulligan attempts to flee, but Shriek goes after him. She corners him and appears to knock him off a ledge with a chain wrapped around his neck. Carnage causes part of the ceiling to fall onto Venom, weakening him just as Carnage grabs and makes his way to the roof to kill her. Venom feels that he and Eddie aren't strong enough to bring them down, but Dan points out that Cletus and Carnage aren't bonded the way Eddie and Venom are, since Carnage keeps trying to hold Cletus down as he fights Carnage's treatment of Shriek. This inspires Venom to rise up and fight back and he stops Carnage from eating him and then saves her from falling. The bell rings and causes the symbiotes to weaken, leaving Eddie and Cletus to fight as men. Just as Carnage and Shriek have them cornered, Venom knocks Shriek off a ledge and sends her plummeting to her demise, causing her screams to bring Venom and Carnage down and she is crushed by a bell. Eddie and Cletus fall, but while Venom manages to use in and Dan to catch Eddie, Cletus and Carnage are separated. Carnage tries crawling back to Cletus, but Venom stops him and devours him first. He grabs Cletus, who tells Eddie that all he wanted was for Eddie to be his friend. Venom declared, kill this guy and chomps Cletus's head off. Eddie and Venom part ways with in and Dan before the police arrive. Meanwhile, Mulligan appears to still be alive and his eyes glow blue just like Shrieks. Later on, Eddie tries to figure out what to do with Venom. Although they initially think about separating for good, Eddie decides to retreat to a tropical island, which Venom appreciates. In the mid-credits scene, Venom tells Eddie that there are other corners of the multiverse that symbiotes can see. Just as Venom tries to demonstrate, a burst of energy seems to teleport them to a new location. On the TV, Eddie and Venom see a news report from J Jonah Jameson about Spider-Man following the events of Far From Home. Venom growls and licks Spidey's image on the screen. Death to you, father. No! Not you, father. You, father. Oh, shit!