Plot

A failed reporter is bonded to an alien entity, one of many symbiotes who have invaded Earth. But the being takes a liking to Earth and decides to protect it.

After a faulty interview with the Life Foundation ruins his career, former reporter Eddie Brock's life is in pieces. Six months later, he comes across the Life Foundation again, and he comes into contact with an alien symbiote and becomes Venom, a parasitic antihero.

Eddie Brock (Tom Hardy) is a famous journalist/reporter who "follows people who don't want to be followed," as he puts it. He comes across the Life Foundation and in an attempt to uncover allegations the foundation received, he loses his entire career. Six months later he is brought back to the foundation by one of their leading scientists. But during his visit, Eddie comes across an alien known as a Symbiote. Venom and the Symbiote, chose to attach and adapt to Eddie's body. However this gets Brock in trouble by Carlton Drake (Riz Ahmed), the leader of the Life Foundation. Eddie/Venom must stop Drake from continuing with his plans of turning the humans en masse into full Symbiotes for his invasion forces.

After choosing to pursue the nefarious Life Foundation Corporation and its visionary CEO, former idealistic reporter Eddie Brock has his back to the wall. Six challenging months later, a defeated Eddie uncovers a shocking secret and unwittingly becomes the host for an amorphous, pitch-black alien life form known as Venom, a powerful interplanetary Symbiote. As a result, Eddie must keep the voracious parasitic organism alive, whether he likes it or not. But with Earth teetering on the brink of destruction, will Eddie survive the poison within?—Nick Riganas

While exploring space for new habitable worlds, a probe belonging to the Life Foundation, a bio-engineering corporation, discovers a comet covered in symbiotic lifeforms. They bring four samples back to Earth, but one sample escapes and causes the ship to crash in Malaysia. The search parties are not able to find the escaped sample, but one of the astronauts on the spaceship is astonishingly found alive near the crash site. The astronaut is shifted into an ambulance, to be taken to a hospital. The Symbiote takes over the body of the astronaut and crashes the ambulance. The Symbiote walks out in the body of the nurse and has the ability to heal human bodies. The Symbiote finds the insignia of the Livfe Foundation and heads towards it. The Symbiote is hungry for meat and keeps changing from one body to the next, and keeps moving towards its destination.

The Life Foundation recovers the other three and transports them to their research facility in San Francisco, where CEO Carlton Drake (Riz Ahmed) (A genius inventor and leader of the Life Foundation experimenting on the Symbiotes) learns that the Symbiotes cannot survive without oxygen-breathing hosts, which often fatally reject the symbiosis unless they are compatible (like organ transplants).

Investigative journalist Eddie Brock (Tom Hardy) reads about Drake's human trials in a classified document in the possession of his fiance Anne Weying (Michelle Williams), an attorney involved in preparing a lawsuit defense for the Life Foundation. Brock confronts Drake with allegations that he runs a space empire and a pharmaceutical empire to fund his space exploration. He recruits the most vulnerable sections of the society for his company's drug tests, by luring them with money and many of them end up losing their life. This leads to both Brock and Weying losing their jobs. Consequently, Weying ends their relationship. Mrs Chen (Peggy Lu) is a convenience store owner where Brock shops. One day the store is burgled and Brock can do nothing but hide. Mrs Chen is very supportive of Brock.

Six months later, Drake is getting closer to achieving successful symbiosis with humans. Skirth (Drake's scientist) had just completed animal trials on rabbits, and Drake wanted to her start human trials, while she felt it was way too soon. Skirth knew that for the symbiosis to take place, a perfect match between the host and the Symbiote is necessary. If the match is not perfect, the host dies, which means many humans would be killed before a perfect human match for the Symbiotes is found. Drake speculates that if humans achieve symbiosis with the alien life form, then they may also be able to endure in space, like the Symbiotes do. Drake wants the human test subjects, on the next test flight to check their survival probability in space with the Symbiote inside them.

Brock is approached by Dora Skirth (Jenny Slate), one of Drake's scientists who disagrees with Drake's methods (of picking random humans and subjecting them to death during experimentation) and wants to help Brock expose him. Skirth says that she will not go to the cops directly, as she is afraid for her family and her life. Skirth tells Brock that Drake's probe into space brought back alien life form back to the planet.

Skirth helps Brock break into the research facility to search for evidence, and he learns that an acquaintance of his, a homeless woman named Maria, has become one of Drake's test subjects. Brock attempts to rescue Maria (Melora Walters), but she attacks him and the Symbiote possessing her transfers from her body to his, leaving her dead. Brock escapes (by displaying super strength, speed and agility), but he soon begins displaying strange symptoms (excessive hunger, eating out of the dumpster and drinking out of the toilet) and reaches out to Weying for help when he starts hearing voices inside his head. Her new boyfriend, Dr. Dan Lewis (Reid Scott), examines Brock and discovers the Symbiote.

Meanwhile, Drake executes Skirth for her betrayal (Drake makes Skirth also reveal the name of the person she brought into the facility) by exposing her to the remaining captive Symbiote, which ultimately dies. This leaves the Symbiote inside Brock as the only known surviving specimen.

Drake sends mercenaries to retrieve the Symbiote from Brock, but it manifests around Brock's body as a monstrous creature that fights off the attackers. The Symbiote also actively protects Brock from the attackers and shelters him from bullets and other life threatening situations.

Taking shelter outside the city, the Symbiote communicates with Brock and introduces itself as Venom. It explains that the comet is an invasion force searching for new worlds where the Symbiotes can possess and devour the inhabitants. Venom offers to spare Brock if he helps the Symbiotes achieve their goal, and Brock soon comes to enjoy the superhuman attributes that the Symbiote gives him.

Brock breaks into his old workplace to turn in evidence of Drake's crimes, but he is surrounded by SWAT officers on the way out and transforms once again to escape. Weying witnesses this transformation and takes Brock back to Lewis's office, where they reveal to Brock that the Symbiote is slowly rotting his internal organs. Brock also admits that the Symbiote has two weaknesses: high-pitched noises and fire. Although the Symbiote claims the organ damage is a fixable part of their symbiosis, Weying uses an MRI machine to weaken the Symbiote long enough for Brock to separate from it. Brock is then captured by Drake's men.

Meanwhile, the fourth Symbiote, Riot, makes its way from Malaysia to San Francisco by hopping from body to body. It bonds with Drake, who agrees to take Riot in a Life Foundation space probe to collect the rest of the Symbiotes and bring them to Earth. Weying reluctantly bonds with Venom so they can free Brock. When Brock and Venom are bonded again, the latter states that he has been convinced to help protect the Earth from his kind through his interactions with Brock, and the pair attempt to stop Riot and Drake with Weying's help. Venom damages the probe as it takes off, causing it to explode and kill both Riot and Drake. Weying believes Brock is no longer bonded to Venom after this, and that the Symbiote also died in the explosion. However, the pair remain secretly bonded and set out to protect the city by killing criminals.

Brock also returns to journalism, and in a mid-credits scene he is invited to interview incarcerated serial killer Cletus Kasady, who promises "carnage" if and when he escapes.