Bluebeard is from a French fable telling the story of a young woman who marries a wealthy aristocrat who had several wives beofre her but no one knows what happened to them. The aristocrat is thought ugly because of his blue beard.
One day the aristocrat announces he is leaving for a trip and he gives his new wife the keys to all the rooms in his house and says to use them freely. Then he gives her one more key and says not to use this one. She vows not to, but as soon as she leaves she goes and opens the door. To her horror she finds the room awash with blood and his other wives bodies. In her surprise she drops the key in blood, and then can't wash the blood off.
Her and her sister (who was visiting her) make plans to leave the next day, but the aristocrat returns unexpectedly. He sees that there is blood on the key and knows she has gone into the room. He is about to kill her when she asks for 15 minutes to say her prayers. He grants her this and her and her sister run and lock themselves in the tower. When the aristocrat is about to break down the door the brother shows up and kills the aristocrat.
The new wife is the sole inheritor to the aristocrats money and gives her sister money for a dowry and her brother money for her brothers' captains commisions. She marries a worthy gentleman.