The House of Dies Drear is a novel by Virginia Hamilton about Thomas Small, an African American boy who moves into a new home that was previously a part of the Underground Railroad. Many believe that the house's caretaker, Mr. Pluto, is the devil. Soon, strange and mysterious things begin to happen in the house after the Smalls move in. Their next door neighbors, the Darrows, act hostilely toward them and they eventually learn that the Darrows are trying to recover treasure from the Underground Railroad tunnel.
Thomas Small is a 13-year-old boy, moving with his family from North Carolina to Ohio. His father is a history professor who has leased the historic home of the abolitionist Dies Drear. The house has been mostly empty for years, and is riddled with hidden passageways that were used to hide escaping slaves on the Underground Railroad. An elderly caretaker called Mr. Pluto lives in a cave on the property, which he has converted into a home. There are rumors that the house is haunted by the ghosts of two escaped slaves who were captured and killed, and by the ghost of Dies Drear himself.
Upon arriving, the Smalls find that Mr. Pluto has already arranged their furniture for them. Thomas meets a boy (Mac Darrow) and his adopted sister (“Pesty”), who regard him as an outsider and don’t warn him about the drop into a hidden passage under the house. Thomas gets lost inside it and hears strange sounds as he scrambles to find a way out. Finally he hears his mother talking and pounds on a passage wall, which opens up into the house. His father warns him not to go exploring the passages, as they might cave in. His parents don’t believe that anyone was in the passages with him, but remove the mechanisms that open the passage just in case.
Thomas explores outside the house near dark, and accidentally strays across the cave Mr. Pluto has converted into his house. Mr. Pluto terrifies Thomas and catches him, unusually strong and fast for such an old man, and chases him back to the house. Pluto apologizes after he realizes Thomas is not one of the local children, who he says often sneak around his home to torment him. He delivers an ominous warning about haunting in the area before he leaves. Thomas is certain that Pluto is hiding something.Thomas decides to sleep on the couch rather than in his new bed room, so that he can see if anyone approaches the door. During the night, someone sneaks into the home through a secret passage and hides a small metal triangles in the door frame of each of the 3 bedrooms. The Smalls find them in the morning, unsure what they mean, though they determine they form an incomplete square with a greek cross inside when put together.
When the Smalls attend the local black church, they are met with a cool reception by the small-town families. Mac Darrow, his father, and his three elder brothers are present and particularly cold. Mr. Pluto attends and Pesty sits with him, as Pesty is one of the only people Mr. Pluto is friendly with. During the sermon, Mr. Pluto behaves oddly and even kneels on the floor despite the protests of one of the Darrows. Thomas is saddened by the unfriendliness of the local people, contrasting it with how guests often visited his family after church in North Carolina.
The family goes to lunch at Mr. Small’s new college, where Thomas and Mr. Small find a fourth triangle in Mr. Small's new office. They arrive home to find that the kitchen has been wrecked. Someone has made a mess of the food all over the floor, the counter, the sink, and the furniture. The dishes are all broken. Mr. Small, furious,suspects Mr. Pluto and takes Thomas with him when he goes to confront the caretaker. Mr. Pluto flees into the cave. While looking for him, Thomas and his father find another secret passage that leads deeper into the cave. Here they find Pesty and Mr. Pluto in a cavern full of historic artwork, tapestries, glasswork, ledgers, and carvings. The cavern is a constant, dry temperature that has preserved the pieces. Mr. Pluto is sitting at an old and fine desk, and begins to confess he is sorry for trying to trick the Smalls and only did it because he was afraid. While talking to Mr. Pluto, they areconfronted by a man who looks just like him. Thomas attacks him in desperation, and he reveals he is actually Mr. Pluto’s son, Mayhew.
Mayhew is an actor, who returned home from the city to help his father protect the secret of Dies Drear’s treasures in the cavern. Mr. Pluto has protected the secret for years, but when he started to get sick he worried that the Darrows would notice and take advantage of his weakness. The Pluto that chased Thomas before was actually Mayhew in disguise, explaining his strength and odd behavior at the house.
The Darrow family has been looking for Dies Drear's collection for years. Mr. Pluto and Mr. Darrow’s father were both descendants of escaped slaves who had passed through Dies Drear’s house, and later returned. Pesty followed Mr. Pluto inside once, but has helped him keep the secret instead of telling the Darrows. Mr. Pluto and Mayhew feared that the Smalls would be like the Darrows and posea threat to the historic artifacts in the cavern, but they now see that Mr. Small has a great appreciation for history and can be trusted with the secret.
Mr. Small explains what happened in the house. Mr. Pluto and Mayhew say it must have been the Darrows trying to drive the Smalls away, and Mayhew explains there is a passage behind the parlor mirror that leads onto the Darrow family’s land that they must have used to get inside. Pesty has mentioned that Mac didn’t want to get involved and Mr. Darrow would not have done it, so it had to be the three older brothers.
Mayhew returns with the Smalls and helps them clean up their kitchen. Together they hatch a plan to scare the Darrows away for good by pretending to be the ghosts of Dies Drear and the escaped slaves. The next day, they set a trap for the Darrows by telling them Mr. Pluto had to be sent to the hospital and will be back in 24 hours. The original plan is to send Mr. Pluto to a hospital for real, as Mayhew worries for his father’s health, but he refuses to go. Mr. Pluto agrees to see a doctor later, but only if he is allowed a part in scaring the Darrow boys. Mr. Pluto also explains the triangles the Darrows hid to scare the Smalls, which are part of a navigation method that was used to guide escaped slaves to places ofsafety along the Underground Railroad.
The men prepare, and lay out in the forest to wait. When the Darrows arrive at Mr. Pluto’s cave in the middle of the night, he confronts them. Mr. Small, Thomas, and Mayhew menace them while dressed as ghosts, and Pesty has used glowing paint to make one of Mr. Pluto’s horses look like a spectre. The Darrows flee in terror, though there is no doubt they will realize it was all fakelater. Their pride is sufficiently hurt.
After the Darrows are driven off, Mr. Small takes to helping Mr. Pluto catalogue the artifacts in the cavern. They agree to keep the secret, at least until that is done and it is ready to show to the historical society. Thomas looks forward to starting school and making friends, possibly including young Mac Darrow.