The Simpsons awaken one morning to discover that they have been robbed. the break-in is just one of a series of crimes attributed to the Springfield Cat Burglar. Residents arm themselves and install security devices. The Neighborhood Watch group elects Homer as its leader.

Homer's group patrols the streets, but its members break more laws than catch criminals. During an interview on Kent Brockman's "Smartline," Homer receives a call from the cat burglar threatening to steal the world's largest cubic zirconia from the Springfield Museum. He stakes out the museum, but is distracted by minors drinking beer. Joining them, he proceeds to get drunk, and the cat burlar steals the zirconia.

Grampa comes forward and indentifies the cat burglar as Mr. Molloy, one of the residents from the retirement home. As citizens storm the home to find their stolen property, Chief Wiggum places Molloy under arrest, Molloy escapes from jail when he sends the townspeople on a wild goose chase to look for money hidden under a "big T."