The novel opens with Roseanne in the present day (sometime around 2007) beginning to write her life story in a journal. She is nearly 100 years old and has been a patient at the Roscommon Regional Mental Hospital since 1957. Her journal details some of her early memories in the town of Sligo, Ireland. She had enjoyed a close relationship with her father, Joe, whom she was very fond of, and many of her early memories involve him. As a child, her father was employed as superintendent of a Catholic graveyard, despite being a Presbyterian. Roseanne notes that her father was well-liked in the town, which helped him attain this job without being a Catholic. His employer, the priest Father Gaunt, would prove to be a pivotal figure in Roseanne’s life.
As Roseanne begins work on her journal, the reader is introduced to Dr. Grene, a senior psychiatrist at Roscommon Mental Hospital. He is around 65 years old and has been working at Roscommon for the past thirty years. His wife, Bet, is distant with him because of troubles they had in their marriage. They were unable to have children, which upset them both, and Dr. Grene had a brief fling outside of their marriage which deeply hurt Bet and turned her away from him. Although Dr. Grene has resided in Ireland and knows he was born of Irish parents, he was adopted and raised in England, so he has often felt like an outsider in both Ireland and England.
The old building that houses the hospital is in great disrepair and will have to be demolished. Dr. Grene is tasked with reviewing the patients to see which of them can be discharged and which should be moved to the new hospital location. He decides to start gently probing Roseanne about her life and how she came to be at the hospital in the first place. He holds her in high regard and they have shared a comfortable and friendly relationship for the years he has been working at the hospital. For this reason, Dr. Grene feels nervous about questioning her too much and decides to tread carefully in his interviews.
Meanwhile, Roseanne has been writing about specific incidents involving her childhood in Sligo during the years of the Irish civil war that took place in the early 1920s, shortly after the First World War. Roseanne is a teenager then, and one night is at the church with her father, Joe, when three young men come to the door carrying with them a dead comrade. One of them is named John Lavelle, and the dead man is his seventeen year old brother, Willie. The men explain that Willie was mercilessly shot dead by a group of Free State soldiers and they would like him to have a proper burial. Joe sends her to fetch Father Gaunt, who obliges and comes to the church. Shortly after arriving back at the church, the group of soldiers that killed Willie barges in and confronts them. An argument ensues but Father Gaunt eventually gets the soldiers to leave him, Roseanne and Joe alone. The soldiers take John and his comrades away and Father Gaunt is angered at Joe for bringing him into the situation.
Not long after this incident, Joe is removed from his job at the graveyard and, having no other choice, takes on the humiliating job of town rat catcher in order to earn money and provide for his family. He is found hung later on in an abandoned cabin and it remains unclear whether he killed himself or was murdered by soldiers on either side of the war. At the same time, Roseanne’s mother has descended into madness and needs to be taken care of. Even though she is only 16, Father Gaunt suggests to Roseanne that she convert to Catholicism and marry. As a prospective husband for Roseanne, he suggests her father’s middle-aged replacement at the graveyard, Joe Brady. Roseanne declines and opts to get a job working as a waitress at a cafe in Sligo instead, which angers Father Gaunt.
Roseanne’s years at the cafe are enjoyable for her and she befriends her fellow waitresses there. They often go dancing together to the local dance hall, where the McNulty brothers, Jack and Tom play in a live band. She gets to know Tom and they begin to date. His family is Catholic and his mother disapproves of Roseanne. Despite Mrs. McNulty’s disapproval, Tom and Roseanne are married in a quiet ceremony outside Sligo. Roseanne is happy with Tom and they love each other.
One day, Roseanne is surprised to come across John Lavelle in town again. He is friendly with her and is sorry he once believed she had given his whereabouts away to the Free State soldiers on that fateful night at the graveyard when she went to fetch Father Gaunt. He asks her to meet him at Knocknarea Mountain the next day and although she fears it won’t look good, she goes to meet him. Roseanne feels a kinship with John because of the death of Willie and her own father. At the mountain, they speak privately and John tells her about how his wife was shot and killed by local police in his hometown while carrying their young twin boys. One of the twins was also shot and the other was dropped and fell on his head. This twin, Sean, survived but was left developmentally challenged. He feels close to Roseanne and tells Sean to look for Roseanne if anything happens to him. As Roseanne and John are speaking, a group of priests comes upon them and immediately suspects them of having improper relations. The next day, Tom doesn’t come home and Father Gaunt and her brother-in-law Jack come to see her, telling her to stay away from Tom while they figure everything out. This turns into a two year stint and Roseanne lives alone and isolated in her cabin, speaking with very few people as she is shunned from society. Eventually, Father Gaunt returns to tell her that her marriage has been annulled on the grounds of insanity and that Roseanne no longer has a husband. She later learns that John Lavelle rejoined the IRA after their meeting and was hung for shooting a policeman.
As the story progresses, Dr. Grene has been trying to piece together evidence on Roseanne. He contacts the old mental hospital in Sligo, where Roseanne was placed before being moved to Roscommon. There, he meets with the doctor to go over her files. He reads a scathing report from Father Gaunt and is inclined to side with Roseanne, knowing that psychiatric hospitals could be cruel and unfair places during the previous century. It is written that Roseanne had a baby that she killed at some point, although Roseanne says she was told the baby went to “Nazareth”. From his visit to Sligo, he realizes that the old orphanage there was called Nazareth House and he books an appointment to see if he can locate the baby.
In Roseanne’s journal, the reader learns how she came to have a child after her marriage was annulled from Tom. While living alone in the hut, a soldier separated from his regiment appears one day. It turns out to be Eneas McNulty, the brother of Tom and Jack whom Roseanne had never met because he was always off somewhere and was an outcast in his family. They bond over being outcast by society and Roseanne sleeps with him, happy to experience human contact again. He goes off to rejoin his regiment and Roseanne is left alone again, quickly realizing that she is pregnant. When she is close to giving birth, she becomes afraid and desperately walks miles to the McNulty house to beg Mrs. McNulty, her former mother-in-law, for help. She is cruelly turned away from the door in a fierce storm and must try to get back home to shelter. On her way, she collapses and gives birth. When she awakens, an ambulance has come for her but the baby is gone. Father Gaunt meets her at the hospital where she is very sick and he tells her that the baby is dead and gone to Nazareth. Shortly after, Roseanne is committed to the Sligo Mental Hospital by Father Gaunt and Mrs. McNulty.
Dr. Grene is saddened to hear of Roseanne’s misfortunes and researches further into what became of her baby. It turns out the baby, a boy, was adopted out to a couple in England and Dr. Grene soon discovers that he himself is that baby. He also pieces together that the old caretaker at the hospital who pays special care to Roseanne, John Keane, is actually John Lavelle's son, Sean who had sought out Roseanne after his father's untimely death. Dr. Grene returns to Roscommon and knows that Roseanne is too old and frail to cast out into the world, even though he believes she does not and never truly did belong in an institution. He brings her to the new hospital where they continue their close friendship and he waits for the right time to tell her that he is her long lost son.
