Dr. Leo Marvin is a successful therapist with a best-selling book out and a gig with a morning show scheduled. He is also very arrogant
He takes on one appointment with a patient, Bob, who has been transferred from therapist to therapist. Bob has pantophobia — he's afraid of everything. Dr. Marvin encourages a first-name basis, as therapists do, and recommends his book to Bob.
Bob's hero-worship for Dr. Marvin begins immediately. Unfortunately for Bob, Dr. Marvin is going on a trip to his vacation house and does not want to bring work along with him. It's a family vacation for a seriously messed-up family. Unfortunately for Dr. Marvin, Bob is not going to give up that easily.
Bob learns where Dr. Marvin will be staying and follows, bringing just his essentials and his goldfish. He has subtle encouragement from the locals, who disapprove of Dr. Marvin and are only too happy to let this lunatic interfere with his peaceful vacation.
The fun begins when Bob and Dr. Marvin's family meet. Bob almost accidentally helps everyone with their problems — except Dr. Marvin, whom he is unwittingly driving over the edge...