The film concerns a writer named Paula Martin (Anna Brecon) who having published a bestseller, retreats to her family's gothic country house, Crow's Hall, to focus on writing a new book. Struggling with Writer's Block along with nightmares of her abusive childhood, she takes on an attractive female assistant named Linda (Jane March). As Paula's nightmares persist, Linda provides her with comfort and support, even allowing Paula to sleep in her bed. When Paula finds Linda editing her novel one morning, she flies into a rage. Linda reacts by murdering Paula's cat. Unaware of the cat's disappearance and feeling guilt for shouting at Linda, Paula apologises to Linda and admits that she is impressed by Linda's additions to the book. Linda offers to write some more of it and give Paula the opportunity to take the day off. Linda then takes control of the book and Paula's life, screaming at her to send the staff home when the noise they make distracts her. Paula, too timid to fight back, meekly obeys Linda and becomes bedridden with Linda locking her in her room. When a successful writer named Robert Gainor (Billy Murray (actor)) comes to the house to interview Paula, Linda answers the door, claiming to be Paula and invites Gainor into the kitchen where they open a bottle of wine and eat some cheese with biscuits. When Gainor asks Linda if he can record their interview, she flirts with him before slashing his throat and revealing that her brother abused her when she was thirteen and she stabbed him to death. She hides Gainor's body in the cellar and tells Paula that he simply came to interview her but Linda told him that she was busy and he left. When the housekeeper, Mrs. Brown (Linda Hayden) finds Gainor's body, Linda kills her too.