Jamaica Inn is a novel by celebrated author Daphne du Maurier. In this novel, Mary Yellan comes to live at Jamaica Inn with her aunt and uncle after the death of her widowed mother. Mary comes to the inn expecting to be reunited with the kind, carefree aunt she met once as a young child. However, Mary arrives to find Jamaica Inn a cold, foreboding place that has earned a reputation fitting to the abusive man who has come to be its landlord. Mary almost immediately begins plotting an escape for herself and her aunt, but quickly realizes she does not know whom she can trust. A novel of mystery, evil, and intrigue, Jamaica Inn is an exciting adventure for readers of all ages.

Mary Yellan has recently buried her mother and sold the family farm in order to fulfill her mother's dying wish that she go to live with her aunt, Patience, in Bodmin. Mary is saddened at having to leave the only home she has ever known, but excited to reconnect with the vivacious aunt she only met once as a child. On her journey, Mary begins to hear rumors that Jamaica Inn, the place where her aunt and uncle now live, is not a place a respectable woman should visit. The driver of her coach tells Mary that coaches once stopped at Jamaica Inn for refreshments and good conversation, but now no one ever stops there.

Mary arrives to meet Joss Merlyn, her uncle. Joss is a large man, with features that speak of a hard life and excesses in alcohol. There is violence in Joss that Mary recognizes from the moment he opens the door. Mary sees it too in her aunt. Patience is no longer happy and carefree, but a skittish, frightened woman. Almost immediately Mary begins to make plans to escape Jamaica Inn, take her aunt, and buy a farm back in Helford where they could both live the rest of their lives in peace.

The first few weeks, Mary spends her mornings helping her aunt do household chores and her afternoons exploring the moors. Jamaica Inn is easy to care for because most of the rooms are used as storage and no customers ever come. Then, one Saturday night, Joss Merlyn has a group of friends to the bar where Mary is expected to act as barmaid. The men are rowdy and crude, making suggestions to Mary that she knows they would act upon if Joss was not there to protect her. After a time, Mary retires to her bedroom above the front porch, sickened and frightened by the men she has spent the evening serving.

During the night, Mary is woken by the noise of wagons moving in the front yard. Mary has been warned to ignore these sounds, but curiosity gets the better of her. Mary watches as the men from the bar move cargo from wagons to the house while moving other boxes to open carts. After a while, Mary sneaks downstairs to get a closer look. Joss is in the bar with Harry the peddler and another man. Mary listens as the man tells Joss that he no longer wants to take part in Joss's schemes. Harry hits the man and leaves him unconscious on the floor. When Joss is alone, he goes upstairs and is joined by a man who was hiding in an upstairs room. Joss speaks to this man about what they should do with the unconscious man in the bar. Mary listens to the conversation and is struck with the impression that they intend to kill the man. After they leave, Mary goes into the bar and finds a rope hanging from the rafters.

Mary is shaken by what she has seen and heard in Jamaica Inn and determined to learn all she can to help bring justice down on her uncle. Squire Bassat, the local law, comes to Jamaica Inn and searches it, but finds nothing. When Joss learns of this visit, he goes for a walk in the moors. Mary follows, hoping to learn something she can use to see Joss arrested for his crimes, but only becomes lost. Mary runs into Francis Davey, the vicar of Altarnun, on the road and he takes her home to feed her before returning her to Jamaica Inn. Mary confides her story in Mr. Davey, but he tells her she does not know enough to go to the law about Joss's activities. However, Mr. Davey promises to help her any time she is in need.

About this same time, Mary meets Jem Merlyn, Joss's younger brother. Mary's immediate impression is that Jem is just like his brother. However, when Mary meets Jem again at his family home, she begins to see differences between the two men. Mary agrees to go to a fair on Christmas Eve with Jem. While there, Jem sells some ponies he has raised, including one he claims to have stolen from Squire Bassat's farm. This horse, Jem ironically sells to Squire Bassat's wife. Mary and Jem spend the rest of the day happily together. However, when Jem goes to get his buggy to take Mary home, he disappears. Frightened that Jem has been arrested, Mary begins to walk home in the rain. Mr. Davey once more comes to her rescue and orders his carriage to take her home.

At Jamaica Inn, Joss and his friends are drunk and waiting in the yard. They kill the carriage driver and grab Mary, questioning where she has been and whom she has been talking to. When Mary tells them she has been to the law, Joss forces her back into the carriage and takes her along with him to the sea. Joss and his friends are going to wreck another ship in order to take its cargo. Mary is on the beach as this happens and is forced to see the sailors drowning as the ship falls apart around them. Everything goes wrong, however, when the sun comes up sooner than the thieves expected. Fights break out and Mary witnesses Joss kill several of his companions in an attempt to escape back into town with the cargo.

Joss realizes he has made a mistake by wrecking that final ship and becomes frightened of some unknown person. Joss begins making plans to leave Jamaica Inn. Harry the peddler comes and attempts to extort his half of the cargo from Joss, but instead finds himself locked in a room at Jamaica Inn. Mary plots to sneak out of her room and tell the vicar of Joss's plans before he can escape justice. However, when Mary gets to Altarnun, she discovers the vicar is not at home. Mary continues her journey into North Hill to speak to Squire Bassat only to learn he is already on his way to Jamaica Inn to arrest Joss. Mary quickly returns to the inn, arriving before the squire and his men. Inside, Mary finds the murdered body of her uncle. When the squire arrives, the find Patience, murdered as well. Harry the peddler, Mary's first choice as suspects, is rescued from his locked prison, effectively clearing him of any wrongdoing.

Mary is taken to the home of Mr. Davey where she rests from her ordeal. Over dinner the following day, the vicar tells Mary that he was the mastermind behind Joss's criminal activities and that he killed Joss to keep him from telling anyone of the vicar's involvement. However, Jem has become involved in the investigation and is sure to learn the identity of the killer at any time. Mr. Davey forces Mary to go with him as he escapes through the moors. A fog settles in, forcing Mary and Mr. Davey to stop until daybreak. As dawn breaks, a search party reaches them. Jem kills Mr. Davey, rescuing Mary. Later, Mary moves in with the Bassat family and begins to make plans to return to Helford. Before she can, however, Mary runs into Jem and decides that her future is at his side.