While exploring space to find new planets inhabited by humans, a Life Foundation bioengineering probe finds a comet covered with symbiotic life forms. They bring four samples to Earth, but one of them escapes and causes the collapse of a shuttle in Malaysia. The Life Foundation recovers the other three and takes them to the San Francisco Research Laboratory where CEO Carlton Drake finds that symbiosis can not survive without oxygen-breathing hosts.
Investigative journalist Eddie Brock reads in a secret document held by his fiancé, Anne Weying, defense lawyer working for Life Foundation, about Drake’s experiments on humans. Brock faces Drake, and soon afterward both he and Anne lose their jobs. Later, Anne decides to break away from Brock. Six months later, Drake is just one step away from getting a symbiosis of success.
Brock is approached by Dora Skirth, one of Drake’s scientists, who disagrees with the methods he uses and wants to help him put the tycoon down. She helps Brock get into the lab to find evidence, and then finds out that his acquaintance, a street woman named Maria, was among Drake’s guinea pigs. He tries to save Mary, but she attacks him violently and transfers the symbiote out of her body into his body, losing his life. Brock runs out of the laboratory with his symbiotic body and then begins to show strange and dangerous symptoms.