Three, intertwining tales offer different perspectives on a day in the life of the Simpsons. First, Homer's attempt to steal a freshly baked brownie results in Marge accidentally cutting off his thumb. They must race to the hospital to have it reattached. In the meantime, Lisa can't find her bike and is left without a ride to school on the day of the big science fair. Her invention, a robot that corrects grammar, can't win first prize unless she enters on time. In her numerous attempts to get to school, she eventually crosses paths with the rest of the family. Meanwhile, Bart and Milhouse uncover a stash of fireworks. When Chief Wiggum catches up to them, he enlists their help in an undercover sting operation, with explosive results. As the mayhem of the day unfolds, it becomes clear how the actions of each family member.