Betty Lou is just an unappreciated housewife who helps out at the town library were she is also unappreciated.The being unappreciated part is where the fun starts. Her husband takes her for granted and spends all his time at his job (police detective), so much so that Betty Lou begins to think he may be having an affair.So she follows him on one of his late night call-ins to a motel and she listens at the window as the police inside discuss a crime scene where a local bad guy has just been killed.On her way home, her dog recovers a pistol (the murder weapon) just barely in the water beside the river. She takes it and puts in her purse (hence the title). She takes the pistol to her husband's station to turn it in, but no one will pay her any attention.After her attempts to get her husband and his fellow officers to listen to her and pay her some attention meet with total indifference, she confesses to having an affair and killing her lover using the information she overheard while hiding outside the motel, after which she starts to get some attention.This movie is (FOTFL) falling on the floor laughing funny, while at the same time pointing out the levels people will go to to just be noticed.