Bob Wiley is a neurotic psychologist who, after being treated by his therapist, becomes obsessed with the idea that every step he takes could lead to a potential disaster. With a series of phobias that would be a therapist's dream, Bob decides to follow his doctor, Dr. Leo Marvin, to his vacation home after the doctor recommends that he take a holiday. Chaos ensues as Bob shows up at the doctor's house, eager to continue his treatment, and starts interfering in Leo's life and that of his family.
The family man, Leo, is on the verge of releasing his new book on mental health, and Bob's arrival couldn't have come at a worse time. As the days go by, the situation becomes increasingly absurd, as Bob's charismatic and unexpectedly charming personality begins to win over Leo's family. From his wife to his children, they all start to see in Bob what they feel is missing in their own lives.
But what will happen to Leo's mental balance? The more he tries to distance himself from Bob, the more Bob becomes a part of his life, leading to a comedic battle where the roles of therapist and patient are unexpectedly reversed. Comical and unforgettable situations multiply, turning Bob into a phenomenon that Leo could never have imagined.