Madame Antoine follows Go Hye-rim, a popular fortune teller who runs a cafe named after Marie Antoinette, claiming she is spiritually connected to the French queen. In reality, she uses her sharp intuition and keen psychological insight to cold-read her clients and solve their romantic troubles. Her life takes a complicated turn when renowned psychotherapist Choi Soo-hyun opens a psychological clinic on the floor right above hers. Soo-hyun, who is emotionally detached and scarred by his past, is conducting a secret psychological experiment to prove that true love does not exist. He targets Hye-rim as the ultimate test subject for his hypothesis, setting up a clash of wits and professional pride between the psychic fraud and the cold scientist. As the experiment progresses, both find their carefully constructed emotional defenses crumbling as genuine feelings begin to develop.