This novel is considered to be one of the great classic Gothic romances, falling into the same category as Rebecca and Jane Eyre. It is also the Cinderella story of a young girl from modest circumstances who realizes her dreams and also overcomes great tragedy after she marries a wealthy, powerful man.

Miranda Wells is a young farm girl filled with romantic notions that have little to do with her everyday life, and while both her parents love her, her mother, Abigail, is the one who is sympathetic to her dreams. Then one day, a letter arrives from Nicholas Van Ryn, a wealthy cousin whom they have never met, inviting her to come and stay at Dragonwick, his estate.

Once she is there, Nicholas decides that Miranda has much to learn, and he bluntly says that he will "make out a map of reading" for her. Then he takes her to meet his wife, Johanna, a dull, obese woman who is preoccupied with food. It is also obvious to her that Mrs. Van Ryn seems to classify her as an "upper servant", and that she will be caring for their daughter Katrine.

At the Fourth of July celebration, Miranda finds herself dancing with Nicholas, as she had hoped to do, when a guest falls on the slippery floor and the music comes to an end for her. Then, Jeff Turner, a young doctor who has nothing but contempt for the Van Ryn's way of life, arrives to take care of the count, and he and Nicholas take stock of one another as they talk.

One day, when Miranda takes Martine to the doctor's office, she walks into a down-renters meeting and she is appalled. Later, when she tells Nicholas about it, he brushes the information aside. On the way home, their carriage is surrounded by a band of tenant farmers disguised as Indians; a bullet shatters two windows and he draws her near as the shot rings out. Once the frightened horses are calmed, Jeff Turner comes to see if anyone has been hurt, saying that the down-renters don't intend to be violent and that the group will deal with the shooter.

Another time, Nicholas sends for the doctor to visit Johanna, who has a heavy cold. Jeff is invited to spend the night there. When Joanna dies a few hours later, he can only assume that acute indigestion has weakened her heart.

One night before the funeral, Miranda is awakened by the sound of Nicholas calling her name. Then, he kisses her passionately and she is frightened by what is happening. When they stand talking by the fire, he places a ring on her finger, the Van Ryn betrothal ring that Johanna never wore. He explains that she must hide the ring and go home for the traditional year-long mourning period, living for the future as he intends to do.

Nicholas comes in the spring as he has planned and Ephraim is amazed that his daughter knew all along that she and Van Ryn would be married and that the wedding ceremony, which will take place in their parlor, has been prearranged. After the wedding, Jeff Turner writes to Miranda unexpectedly, telling her that he has joined the army and will be leaving for Mexico. She has no idea that he was stunned and angry when he heard about her wedding, and that he didn't want to think about her being married to another man.

The summer heat becomes oppressive, and Miranda and Nicholas travel up the Hudson to Pine Orchard Mountain House and she meets Peggy, a likeable Irish immigrant. Her bond with Peggy grows stronger, and Miranda is determined to have the woman as her maid and confidant when she and Nicholas return to Dragonwyck. When he ridicules the idea, she blurts out the fact that she is pregnant, and he is so elated that he is willing to give her anything she asks for.

After he returns from the war, Jeff finds himself summoned to Dragonwyck when Nicholas appears at his door to ask his help, and a baby boy is born the following morning. The doctor also determines that the baby will not live long because his heart is defective, and when he brings Nicholas the grim news, he is totally ignored and asked to leave without seeing Miranda.

One day, the Van Ryns are invited to dine with the Vandergraves and attend a performance of "Macbeth" afterwards. At the time, there is an ongoing feud between two rival factions staging two different versions of the play, one headed by an English actor, favored by the gentry, and another, led by an American actor, favored by the general public—and class warfare is brewing.

When Van Ryn foolishly confronts the demonstrators afterwards, a boy douses him with a bucket of water, and he retaliates by grabbing a soldier's rifle and shooting him. More stones are thrown as the crowd disperses, and one of them hits Nicholas in the chest, forcing him to the ground.

When Nicholas comes home earlier than expected from a trip to New York, Peggy sends to Dr. Turner for help, and both he and Miranda realize that Nicholas is carrying a gun. When Van Ryn draws his pistol and Miranda manages to knock it out of his hand, the two men struggle and Jeff ties him up with a bell rope.

Once they are on the Mary Clinton, Nicholas who is free again, makes the boat stop by hanging a red flag from the tower. Later, the center section of the boat bursts into flames and he carries Miranda to safety. She also contracts pneumonia as of the result of the tragedy, and when she is fully conscious, she senses instinctively that Nicholas is dead and discovers she is the heir to his estate.

Right before Christmas, Miranda and Jeff are married, and since the two are really a team, they decide to move to California, where doctors are sorely needed, both resolving to never look back.