As Lighthouse begins we hear in darkness the sound of seagulls and a bell from a bouy. Aggie, a woman in her thirties, speaks from a wooden chair as a light passes across her like the revolving beacon of a lighthouse, creating regularly spaced intervals of light and darkness. She says that people told her she would go mad, trapped in a lighthouse, but she thought that with her blue-eyed husband and three small children she would be content. She says she was very happy at first but then she began to see things, something slithering across the floor. She tells her husband that there are snakes in the lighthouse, but he doesn’t believe her, and the snakes are so fast that no one could see them. She had nightmares and couldn’t sleep as she prowled the lighthouse with a flashlight at night. She decided that the snakes were after her children and one night stepped on something that caused a horrible, stabbing pain in her heel. Her husband tells her she stepped on a walnut shell and was not bitten by a snake. She feels hate toward her husband and thinks that she has been inoculated with the wisdom of the serpent. When she fell asleep she dreamed that snakes were everywhere in the lighthouse. Realizing she had to save her children, she threw them from the windows. She then tells us, after a silence, that she was taken to a place where she couldn’t hear the sea. They tell her the children are dead. When she asks if the snakes killed them she is told that there are no snakes in the lighthouse. But all she can see is a snake from her dream, a snake with cold blue eyes.