Protagonist and first-person narrator Frank McCourt begins his memoir of his early life in Limerick, Ireland, with a description of how his parents Angela Sheehan and Malachy McCourt met in New York City and were forced to marry by Angela's cousins Delia and Philomena after Angela became pregnant with Frank.
Things turn bad almost immediately. Malachy can't find work in Depression era New York City and any money he does earn goes into the pubs of New York. Angela struggles to feed her family and relies heavily on her Brooklyn neighbors for help. Malachy is steadier after the birth of Margaret but the baby dies shortly and Angela falls into a deep depression. The cousins save the day once more and arrange for the McCourts to return to Ireland and it's here that things go from bad to worse.
Angela's mother "Grandma" is not happy to see her daughter back in Ireland with a ne'r do well husband and four young children but helps them find lodgings. Malachy continues his cycle of finding work, drinking, and losing work. Soon, Frank's little twin brothers Oliver and Eugene die from pneumonia caused by poor living conditions and the lack of nutritious food.
Frank describes his life of horror in Limerick and makes it more palatable with large doses of humor. For instance, the family has to sleep on one mattress that is filled with fleas and they run and jump around in the lane outside. Their house floods but they move upstairs and call it Italy because it is warm and dry. Malachy takes time with his son and tells him stories and sings him songs of Irish heroes but continues to drink heavily to the great economic detriment of the family. Soon Angela gives birth to two more sons, Michael and Alphie.
Although Frank and his brother Malachy Jr. initially experience a difficult time at school because they are "yanks," in time Frank becomes one of the brightest boys in school and demonstrates a natural ability for reading and writing. He has no trouble with studying the catechism for his first Communion and Confirmation. At the age of ten he falls ill with typhoid fever and, near death, he must be hospitalized. Here a girl dying from diphtheria introduces him to Shakespeare and he is immediately struck by the brilliant words. This serves him well in school.
His father Malachy leaves the family during World War II to work in a British factory with the intent of sending home his wages but while the families prosper around them from fathers working in England, Malachy never sends money home and the McCourts sink even deeper into poverty, now having to rely on public aid. Angela on occasion must stand outside a Church begging for the remains of the priest's dinner. When she becomes ill, Frank must care for the family and is forced to steal food and milk from outside Limerick's richer houses.
By the time he is thirteen, Frank is working for his neighbor Mr. Hannon delivering coal. The boy always has some job or other going on while he goes to school. He works reading the newspaper for the Buddhist Mr. Timoney, delivering newspapers for his nasty Uncle Ab, delivering telegrams as a messenger boy at the post office, writing collection letters for the mean-spirited Mrs. Finucane, and delivering newspapers once again for Mr. McCaffrey at Eason's shop. The youngster is excited about working because it makes him feel like a man and it helps him feed his family.
Eventually, the McCourts get evicted after burning down one of the house's walls for fuel and are forced to move in with Angela's cousin Laman Griffin who treats Frank with great meanness. Angela also begins sleeping with Laman which makes Frank angry and after Laman beats him Frank is forced to move in with his uncle Ab, where he very nearly starves.
Frank suffers from guilt over his sexual feelings which are constantly in direct opposition to the Catholic Church's teachings. On one occasion while delivering a telegram he encounters Teresa Carmody who suffers from consumption. The girl, who knows she is going to die, takes Frank inside her house and the youngsters make love. Frank is torn by the wonderful feelings of love and the resultant horrible guilt. Soon after, Teresa dies and Frank suffers terribly with guilt until a priest he meets at St. Francis's Church hears his confession and grants him forgiveness.
However, underneath it all Frank dreams of returning to America, the land of his birth and begins to save money from his wages for his ticket. One night, Mrs. Fineucne dies and Frank robs the money that she makes from the poor in Limerick and flings her ledger into the river so her customers will never have to pay. Then he has enough money for his fare and after a departing party leaves Cork for New York.
Upon his arrival, the ship, The Irish Oak, is forced to dock in Albany. On the way up, Frank attends a party on shore where he meets an American woman named Freida with whom he has a sexual encounter. He is able to put aside his feelings of guilt and suddenly the world looks very bright.