Full story
A spacecraft owned by the Life Foundation, billionaire Carlton Drake's company, returns from space with samples of creatures found on a comet: symbiotes. On reentry, it crashes in Malaysia and one of them escapes, hopping from body to body. The other three reach the foundation's lab in San Francisco. Drake learns they need a human host to survive on Earth, and that the host almost always dies.
Eddie Brock is an investigative reporter known for never letting a story go. He uses a confidential file from the laptop of his fiancée, lawyer Anne Weying, to corner Drake in an interview about illegal human testing. The fallout: Eddie and Anne both lose their jobs, and she ends the engagement. Six months later, Eddie is broke and drifting. Scientist Dora Skirth reaches out and sneaks him into the lab. There he recognizes Maria, a homeless woman he knows, locked in a cell. When he tries to help her, the symbiote inside her jumps to Eddie.
Eddie starts hearing a voice, eating nonstop and showing unreal strength. Drake's goons come after him, and the symbiote emerges in full: a huge, toothy monster that introduces itself as Venom. Eddie learns the creature wants to pave the way for more of its kind to come devour Earth. Anne, now dating doctor Dan Lewis, helps Eddie pull the symbiote out of his body using the noise of an MRI machine. Soon after, Drake's men capture Eddie.
Meanwhile, the escaped symbiote, Riot, reaches San Francisco and bonds with Drake. The plan is to launch a new rocket to bring back more symbiotes. Venom, who ended up in Anne's body, uses her to free Eddie and goes back to him. Then Venom changes his mind: on Earth, he says, he feels different, because on his planet he was a loser too, just like Eddie. The two decide to protect the world.
Eddie and Venom take on Drake and Riot at the launch pad. The fight moves to the side of the rocket as it lifts off. Venom rips open the fuel tank, and the explosion kills Drake and Riot. Venom seems to die shielding Eddie, but survives hidden inside him. Eddie goes back to reporting and makes peace with Anne without telling her Venom is alive. In the final scene, the pair devour a robber at a neighborhood store. In the mid-credits scene, Eddie interviews serial killer Cletus Kasady in prison, who promises that when he gets out there will be carnage. That is left open.