On a family trip the the Springfield Knowledgium, Marge sees that Chief Wiggum's son, Ralph, has no frineds. Feeling sorry for him, Marge volunteers an embarrassed Bart to be his new pal, setting a play date for them

At Ralph's house, Bart discovers that Chief Wiggum has a master key to all the locks in the city. The next night, he and Ralph sneak out and run rampant through Springfield, using the key. They run into Jimbo, Dolph, Kearney, and Nelson. In the hopes of looking cool, Bart tells them about the keyand takes off to an abandoned penitentiary to sneak around. Before they go in, a scared Ralph says he wants to go home. Bart decides he can't leave his friend behind, but the bullies throw the master key into the prison.

When Bart and Ralph go in to retrieve the key, they discover and activate the jail's electric chair to see how it works. The next afternoon, the mayor holds a press conference from the jail to annouce its reopening. He straps himself into the electric chair to demonstrate what Springfield criminals could face. Bart tries to call the jail to warn them that the chair is activated, but the line is busy. Ralph suugests they ask Lisa what to do. Lisa has them write out a note that says "The electric chair is on," and tie it to a model rocket, which they fire at the prison. The rocket lands in Montgomery Burns's office. Burns reads the note and is outraged that the prison has been receiving free electricity. He turns off the power, saving the mayor.