It’s High Noon.

Marge Simpson lies on a therapist's couch while a figure in a dark hooded mask appears outside the window, holding a knife and making threatening gestures; the figure then changes to a man in a cowboy hat and blue uniform, who also holds a knife and gestures threateningly, before Marge sits up in shock. The scene takes place in a therapist's office with a large window looking out onto a bright sky.