Dr. Dan Potter is the replacement for Dr. Harry Merton, a psychiatrist at Dr. Leo Bain's psychiatric hospital. Dr. Merton has taken a position at a psychiatric hospital in the nearby city of Philadelphia. Dan, his wife Nell, and daughter Lyla, have recently moved into a house in the area. Dan's sister Toni arrives for a visit. Leo operates the haven through very lenient methods. The 3rd floor patients--paranoia former POW Frank Hawkes, pyromaniac preacher Byron "Preacher" Sutcliff, obese child molester Ronald Elster, and homicidal maniac John "The Bleeder" Skagg--initially treat Dan with mixed hostility. Dan learns from staff worker Ray Curtis that the 3rd floor patients believe he has killed Dr. Merton. Later, the four men on the 3rd floor talk of killing Dr Potter.