The story starts with a man going into a fortune teller's tent; a dangling tassel knocks his glasses off, there is a brief flash. The story then has a flashback: some people are trying to capture(?) someone for some reason but he has very good (hypnotic?) defenses. They learn he is pretending to be a fortune teller, and the protagonist is given a pair of glasses to protect him against being hypnotised. He is told not to remove the glasses under any circumstances. The story ends as it began: he goes into the fortune teller's tent; a dangling tassel knocks his glasses off, there is a brief flash...
Happy Ending by Henry Kuttner
Quarra Vee and his faithful sidekick, Tharn, travel into the past to capture a rogue robot. The "past" in this case is our present time. The robot is in a circus, pretending to be a gypsy fortune teller.
The robot has telepathic brain washing powers. Vee wears anti brainwashing glasses, but they are knocked off by a rope. The robot hypnotizes Vee in to thinking Vee is a native of our present, instead of a visitor from the future.