Lorna Gale hires former secretary Agnes Langley as a live-in caretaker for the empty Gale estate in Montecito, CA. As the previous caretaker, Lorna’s cousin Jennifer Brown, has apparently disappeared without notice, Lorna asks Agnes to pack up her belongings. Later the same evening, Lorna urges her friend, local innkeeper and grocery store owner Jim Hollis, to look in on Agnes from time to time. Agnes is curious about Jennifer’s disappearance, and after reading Jennifer’s diary, she is frightened by noises in the deserted house. One evening, Jim delivers Agnes’ grocery order as a means to introduce himself, and when she reveals her fears of a prowler, he searches the grounds with a flashlight but finds no one. Agnes stops by the grocery store the next day to pick up more items and hears the local gossip about Jennifer’s disappearance. Her curiosity piqued, Agnes continues to read the diary, explores the house and becomes riveted by a broken record left behind by Jennifer. When Orin Slade, Jim’s young handyman, comes by to fix the heater, he relates a rumor that Jennifer had worked for a prominent attorney and that she was suspected of stealing documents after the attorney committed suicide. Agnes’ obsession with Jennifer prompts her to refuse a dinner invitation from Jim so she can go to a Santa Barbara music store nearby and listen to a recording of Jennifer’s favorite music. Sometime later, Agnes searches an office in the house and finds a bank book revealing a record of regular deposits and a high end balance. Assuming the book belonged to Jennifer although no name is recorded in it, Agnes shows it to Jim and theorizes that Jennifer was a blackmailer who ran off with the money. Jim dashes her theory by noting that no withdrawals are recorded. When Agnes then concludes that Jennifer died in the house, Jim insists that they search the house to permanently allay her fears. Again finding nothing unusual, Jim asks Agnes to talk about herself, and she reveals that she was once cruelly jilted. Although Agnes refuses Jim’s entreaties to stay at his inn rather than the house, she agrees to attend a dance at the inn that night. Jim later warns Orin to stay away from Agnes and to stop feeding her rumors about Jennifer. That afternoon, Lorna calls and tells Jim she wants to straighten out the “Jennifer problem,” but insists on waiting until she can talk with him in person the next day. While Agnes and Jim dance at the party that night, Orin secretly searches Jim’s office and finds the bank book in his desk. After the party, Agnes and Jim seal their burgeoning romance with a kiss. The next evening, Agnes waits for Jim to pick her up for a date, but when he is late, she starts rummaging through Jennifer’s belongings and finds a note indicating that Jennifer thought someone was after her, and that she planned on hiding in the furnace room. Orin appears unexpectedly and, based on Jim’s warning and the bank book, implicates Jim in Jennifer’s disappearance. Agnes insists that he leave, then goes down into the furnace room to search for Jennifer’s body. She is terrified when she sees a woman’s face appear under a pool of water, and runs away from Jim when he arrives. Jim, who has just spoken with Lorna, catches Agnes and reveals the secret Lorna has been keeping in hopes of saving her family from disgrace: that Jennifer was insane and had been institutionalized, and has just died at the sanitarium. Jim proves that the face Agnes saw in the water was her own reflection, and she finally realizes that her imagination has been her own worst enemy. Agnes and Jim re-enter the house together.