The Simpsons Season 5 Episode 11

Springfield is hit by a spate of burglaries with the Simpsons among the victims. Wiggum is as useless as ever so Homer forms a vigilante posse,especially to guard a zirconia from the museum,having been been tipped off that it will be stolen. Needless to say Homer is as useless as Wiggum and the zirconia is stolen. However Grandpa catches the burglar,Molloy,a suave resident of the Retirement Castle,who returns the stolen goods but makes his escape from prison whilst sending the citizens on a wild goose chase for non-existent treasure.