Peter gets home after being bitten by a genetically-engineered spider during a school field trip. He falls ill from the spider's venom, and while he's asleep the venom alters his genetic makeup. He wakes up to find his body has changed dramatically overnight.
Before dropping Peter off to school, Uncle Ben speaks with him for a few minutes in the car. He tells Peter how critical these years of his life are and urges him to think about the kind of person he wants to be when he grows up.