Mrs. Krabappel takes Bart's class on a field trip to the Springfield Nuclear Power Plant, where everybody watches as Homer crashes an electric cart into a cooling vent and is fired. Homer searches for a new job without success. Feeling like a failure, he writes a suicide note to his family and decides to end his life by attaching a boulder to himself and jumping off a bridge.
Lisa finds Homer's note and alerts the family. They hurry to the bridge to save him, but they are almost run over by a speeding truck. Homer pulls them to safety just in time, and he is suddenly filled with a new reason to live: to place a stop sign at the dangerous intersection. After successfully petitioning the city council, Homer embarks on a public safety crusade that involves placing speed bumps and warning signs throughout the town.
Unsatisfied with his own efforts, Homer takes on the biggest danger in Springfield, the nuclear power plant. After Homer rallies people to his cause, Mr. Burns decides to end the furor he is creating by offering him a new position as the plant safety inspector, along with a higher salary. Homer, torn between his principles and his livelihood, tearfully tells his followers that they must fight their battles alone from this point on and takes the job.