On a school trip, high school senior Peter Parker visits a Columbia University genetics laboratory with his friend Harry Osborn and his crush Mary Jane Watson. There, Peter is bitten by a genetically engineered “super spider” that escaped from containment and seemingly falls ill after returning home. Meanwhile, Harry’s scientist father Norman Osborn, owner of Oscorp, tries to secure an important military contract. He experiments on himself with an unstable performance-enhancing chemical and goes insane, killing his assistant.
The next morning, Peter finds he is no longer near-sighted and his body has metamorphosized into a more muscular physique. At school, he finds that he can shoot webs out of his wrists, and that his quickened reflexes let him avoid injury during a confrontation with bully Flash Thompson. Peter discovers he has developed superhuman speed and strength, the ability to stick to surfaces, and a heightened ability to sense danger.
Brushing off his uncle Ben’s advice that “with great power comes great responsibility”, Peter considers impressing Mary Jane with a car. He enters an underground wrestling tournament to raise the money and wins his first match, but the promoter cheats him of his earnings. When a thief suddenly robs the promoter’s office, Peter allows him to escape in retaliation. Moments later, he discovers Ben was carjacked and killed. Peter pursues and confronts the carjacker, only to realize it was the thief he let escape. After Peter disarms him, the carjacker flees but dies after falling out a window. Meanwhile, a crazed Norman interrupts a military experiment by Oscorp’s corporate rival Quest Aerospace and kills several people.