"Bluebeard" is a bit like "Cupid and Psyche" gone horribly wrong.
Picture this: Psyche's sisters convince her to break her promise to her husband and look at him by lamplight to find out if he's a monster. She takes their advice, and shines a light on her husband while he's sleeping. Turns out, she married a lumpy, purple monster with festering skin. Horrified, she spills some oil from her lamp on him. He wakes up and roars, "Wife, you have betrayed me! Now you must die!"
Well, that's kind of what happens in "Bluebeard." There's this wealthy man with a blue beard, and he gives his young wife everything she could possibly want. He just has one requirement: she cannot go into a certain room in their house. (Sounds like Cupid, right? He only has one requirement of Psyche.) When he's away from home, the girl's curiosity wins out and she goes into the forbidden room. What does she find? Tons of blood and the remains of his previous wives. Eek! In the end, she escapes with her life, but she definitely doesn't get a happily ever after with Prince Charming.