The film opens with a young girl winding up a mechanical clown toy in an upstairs window, then she descends to a lower floor window to greet her mother, Julia Lofting (Mia Farrow). During breakfast with her family, her daughter Kate (Sophie Ward) begins to choke on her food. Unable to dislodge the food, Julia attempts to save her by performing a tracheotomy which results in the child's bleeding to death.
Julia leaves her husband Magnus (Keir Dullea) and moves to a new house with an upstairs room containing a child's possessions. In the park, Julia sees a young girl that she believes is Kate but the child disappears. Unusual things happen to take place in the house such as strange noises and appliances turning on by themselves. Later, Julia again sees the girl in the park and finds a mutilated turtle and knife where she stood.
Julia lets Magnus' sister Lily use her house to conduct a seance. Mrs. Flood, the medium, explains that spirits need to control someone to carry out physical acts. During the seance, the medium becomes frightened and tells Julia to leave the house immediately. Moments later, one of Lily's friends falls down the stairs before Mrs. Flood can explain what she saw. While Julia is out, Magnus breaks into her house. He sees something and follows it to the basement where he falls from the staircase, fatally cutting his throat on a broken bottle.
A neighbor tells Julia the house once belonged to Heather Rudge, who moved away after her daughter Olivia died. Julia visits Mrs. Flood who tells her that during the séance she had a vision of a boy in the park, bleeding to death. Julia finds an article about Geoffrey Braden, a young boy who was murdered in the park. Julia visits Geoffrey's mother, Greta Braden, who says a vagrant was executed for the crime but other children in the park murdered her son. She says she and her companion have been following the lives of the children. She asks Julia to visit the remaining two, now adults: Captain Paul Winter and David Swift.
Julia visits Swift, an alcoholic, who confesses that Olivia had power over him and the other children. She made them each kill an animal, and watch as she murdered Geoffrey. He says he told only Mrs. Rudge. Later, as Swift leaves his apartment, he slips on a broken bottle in the stairwell and he falls to his death.
Julia tells her friend, Mark (Tom Conti) what she has discovered but he doesn't believe her. That evening, he is electrocuted by a lamp falling into his bath.
Julia visits Mrs. Rudge in a psychiatric home. Mrs. Rudge confesses that she killed Olivia after learning of the murder. As Julia leaves she looks over her shoulder at Mrs. Rudge, who sees Olivia's eyes and dies of a fright-induced heart attack.
At home, Julia sees Olivia, first in the bathroom mirror and then in the living room playing with the clown toy. She takes it from her, offers her a hug and asks her to stay. Julia is then seen bleeding to death, her throat apparently cut on the sharp edges of the clown's cymbals.Mia Farrow as Julia Lofting
Keir Dullea as Magnus Lofting
Tom Conti as Mark Berkeley
Jill Bennett as Lily Lofting
Robin Gammell as David Swift
Cathleen Nesbitt as Heather Rudge
Anna Wing as Rosa Flood
Edward Hardwicke as Captain Paul Winter
Mary Morris as Greta Braden
Pauline Jameson as Claudia Branscombe
Arthur Howard as Piggott
Peter Sallis as Jeffrey Branscombe
Damaris Hayman as Miss Pinner
Sophie Ward as Kate Lofting
Hilda Fenemore as Katherine
Nigel Havers as Estate Agent
Samantha Gates as Olivia Rudge
Denis Lill as Doctor
Julian Fellowes as Library Assistant
Michael Bilton as Salesman
Yvonne Edgell as Mrs. Flood's Niece
Robert Farrant as Receptionist
Oliver Maguire as Nurse
Susan Porrett as Mrs. Ward
John A. Tinn as Customer
Elizabeth Weaver as Mother in Showroom
The film was originally released in England as Full Circle but fared poorly at the box office. It was released in the United States under the title The Haunting of Julia in 1981, but still failed to find its audience.