Dr. Faraday lives in Lidcote, England, where he spends his days tending to patients. One day, he is called out to Hundreds Hall, a once-grand manor home. Faraday went to Hundreds as a child for Empire Day, where he was presented with a medal. Ever since, the house has held a powerful allure over him, and he is eager to see what has become of it. Faraday goes to Hundreds and meets Mrs. Ayers, the house matriarch, as well as her adult children, Roderick and Caroline. These three people are the only surviving members of the Ayers household. Colonel Ayers, the house patriarch, and Susan Ayers, Mrs. Ayers’ firstborn daughter, are both dead. Susan’s death was particularly tragic because she died from diphtheria at only seven years old.
Although Faraday is glad to see Hundreds Hall and meet the Ayers family, he is surprised at the manor’s condition. Over the years, Hundreds Hall has started to fall apart. Many of the rooms are boarded up, everything looks dull, and it is clear that the Ayerses are running out of money. Nonetheless, Faraday finds himself wanting to see more of the home. As such, he decides to offer Roderick electric therapy on his leg. Roderick is a World War II veteran who was injured in the war, and Faraday offers the therapy for free. Roderick accepts and Faraday starts coming out to Hundreds at least once per week for the therapy sessions.
One day, Mrs. Ayers decides to throw a party at Hundreds in the hopes of attracting a suitor for Caroline. Throughout the novel, Faraday describes Caroline as a “plain” girl, and given the state of Hundreds, she has a difficult time finding a husband. The night of the party, everything goes well at the start, except Roderick is absent for some reason. However, the party abruptly ends when Gyp, Caroline’s normally well-behaved dog, bites a little girl (Gillian Baker-Hyde) in the face. Luckily, Faraday is present to help Gillian and stop the bleeding. However, the bite starts a feud between the Ayers family and the Baker-Hyde family. Eventually, in an attempt to avoid going to court, Mrs. Ayers decides to have Gyp put down, much to Caroline’s dismay. Faraday performs the task himself.
After the party, Roderick begins to act unlike himself. He is more irritable than normal, and eventually he stops accepting treatment from Faraday. Because of this, Faraday spends less time at Hundreds than usual. One day, while driving around town, Faraday sees Roderick looking tired and paranoid. He invites Roderick to his home, and Roderick warily accepts. There, Faraday gives Roderick a physical examination and asks him what is wrong. At first, Roderick does not want to tell him, but eventually he tells Faraday that there is an evil presence haunting him, which he must constantly guard against. Apparently, the night of the party, the presence assaulted him, which is why he did not join the guests. In response, Faraday tells Roderick he is delusional and tries to give him pills to help him sleep. Roderick gets angry, rejects Faraday’s help, and leaves. Feeling he needs to do something, Faraday tells Caroline about Roderick’s story. Unfortunately, Roderick finds out that Faraday broke his promise, which only makes matters worse. One night, Roderick’s room catches on fire. Caroline puts out the fire, but the experience leaves her shaken. She thinks Roderick might have started it, and she tells her theory to Faraday. Faraday thinks she might be right and so he has Roderick placed in a mental institution.
Following Roderick’s departure, life at Hundreds is normal for some time. One night, Faraday takes Caroline to a dance because he hopes it will cheer her up. Caroline accepts the invitation and has a great time. While Caroline dances, one of Faraday’s colleagues, Dr. Seeley, suggests that he romantically pursue Caroline. After the dance, Caroline and Faraday become affectionate with each other, until Caroline decides she doesn’t want to go any further physically. Her rejection hurts Faraday, and he cannot figure out whether he likes Caroline or not. Around the same time, odd occurrences start happening at Hundreds again. Objects move around, telephones ring but no one is on the other end, and the Ayerses think they hear things that are not there. In a particularly terrifying moment, Mrs. Ayers gets trapped in the old family nursery and cannot get out. Out of fear, she breaks a window to get Caroline’s attention and cuts herself in the process. Faraday tends to her wounds and tells Caroline to keep an eye on her.
Faraday continues to pursue Caroline, though neither of them seem to know what they want. Eventually, he asks Caroline to marry him, and she hesitantly accepts. Not long after, Caroline tells Faraday that she thinks a poltergeist haunts Hundreds Hall. She shows him some books—a blend of science and the paranormal—which say that a poltergeist forms because of a powerful unconscious mind. Faraday dismisses the theory as pseudoscientific nonsense and tells Caroline to disregard it.
After Mrs. Ayers recovers from the nursery incident, Faraday decides to ask her about it. Mrs. Ayers says that the ghost of her deceased daughter, Susan, haunts her and is with her at all times, including that day in the nursery. She tells Faraday that Susan is often unkind; then, suddenly, blood shows up underneath her clothing. Faraday thinks Mrs. Ayers is insane and that she’s purposefully injured herself. As such, he decides she should be committed to an institution, just like Roderick. He informs Caroline of his plan and makes her promise to keep an eye on Mrs. Ayers until the next day. However, Caroline leaves her mother alone in the middle of the night, and, when she comes back, Mrs. Ayers is dead. Although her death is officially ruled a suicide, the circumstances surrounding it are strange. When she died, Mrs. Ayers had lots of cuts, bruises, and something that looked like bite marks all over her body.
After Mrs. Ayers dies, Faraday pressures Caroline about setting a wedding date. Caroline gives into the pressure briefly, but then calls off the wedding when she learns that Faraday wants to continue living at Hundreds. Faraday tries to convince Caroline to take him back, but she refuses. Her rejection enrages Faraday, and he hurls crude insults at her.
One night, Faraday drives out to see a patient. On his way home, he pulls over near a pond that is not too far away from Hundreds and decides to sleep in his car because he is tired. The same night, Caroline dies from what looks like a suicide attempt. Betty, the Ayers family maid, finds Caroline’s body and reports it to the authorities. Because of the strange circumstances of Caroline’s death, Faraday must attend a formal inquest. At the inquest, Betty tells the judge that she thinks a supernatural force killed Caroline because Caroline uttered the word “you” just before she died. Betty’s theory startles the judge, and he asks Faraday if Caroline believed in ghosts. Faraday says that she did. Then, the judge asks Faraday what he thinks happened. Faraday tells the judge that he believes Caroline committed suicide even though, in reality, he does not know what to think anymore. With Faraday’s testimony in mind, Caroline’s death is officially ruled a suicide.
Several years later, Faraday still finds himself visiting Hundreds Hall. No one bought the home after Caroline’s death, and he still has a key, so he goes to Hundreds by himself and walks around. One day, Faraday thinks he senses the evil entity that supposedly haunts Hundreds. However, when he turns around, all he sees is his reflection.