Mastr'Antonio Miciaccio caretaker and shoemaker is devoted to Saint John Beheaded and is trying to find out who has been stealing the oil that keeps the candle to the saint burning. He also does not approve of his daughter's boy friend and he does not want him to marry her.

The well off daughter of a tenor breaks up a romance with a helpful youth from a misunderstanding. But she continues to cover him with his gambling debts despite her delicate health.