The plot follows would-be opera singer Paula, who, after years of running from the memory of her aunt's terrible murder, finds solace in the arms of a man called George Anton. The two marry, and it seems like things are off to a good start until, slowly, a series of bizarre events lead Paula to start doubting her sanity, an idea her new husband does everything in his power to fuel. The title itself comes from a famous scene in which Paula notices that the lights in the house have gone dim and flicker, only to be told that she's imagining things. In the end, of course, both Paula and the audience learn that she was right all along: George isn't actually who he says he is, and the strange incidents are of his own making. He, like countless men before and after him, has a vested interest in making a woman doubt everything she knows about herself, to the point where she almost truly does go insane.