Before the start of the main part of the novel the author tells his readers about his native city named Salem and his ancestors who were zealous puritans, his work as the customs officer and his doubts that this work could be an obstacle on his way to Heaven, as such a soulless institution inhibits the very immortal souls of its workers.
One day, checking the huge mountain of outdated papers stored in the archive room of the customary, the author finds a manuscript written by the man named Jonathan Pew who died eighty years ago. It is the story of a woman named Hester Prynne who lived during the end of the 17th century. Inside the manuscript there is also a piece of fabric with the embroidered scarlet letter “A” that looks like a real masterpiece. The author, feeling strange excitement, places it on his chest and feels the letter burning his skin. After his retirement, the author decides to write a novel about Hester’s story.
The novel starts from the moment when Hester Prynne exits the Boston prison with a newborn baby in her arms. She wears a beautiful dress that she sewed by herself while imprisoned. On the chest of the dress there is an embroidered scarlet letter “A” for “Adulteress”. But the woman is so stunningly beautiful and confident and the embroidery is so amazing that it looks more like a precious ornament than a sign of a shame.
The people of Boston gathered on the streets to mock and condemn Hester for her deed. She is taken to main square heading a shame parade and there she should stand until one o’clock while everyone can call her names, humiliate and disgrace her. She deserves such a punishment for not only her adultery (her husband went M.I.A. two years ago after all and she sincerely considered him dead) but for refusal to name the father of her baby daughter.
Standing in the middle of the hostile crowd Hester gathers all her will not to break. She recalls her past life, her childhood in England and an elderly scientist she married because of duty but not love. Looking at the people Hester notices a man she expects to see the least - her husband. He looks much older now but she still recognizes him. He, in his turn, asks the crowd about who is the poor woman. The people are surprised that he didn’t hear about Hester’s adultery before and tell him that she is a wife of an English scientist who sent her to America ahead of him to follow her later. Hester didn’t receive any news from him in two years and decided that he probably died. The court took into consideration that fact, so Hester won’t be executed after that shame walk but just will be obliged to wear the red “A” as a sign of her disgrace for all her life. Nevertheless, the people are dissatisfied with that decision: neither had Hester repented nor told the name of the father of the child. The Boston priest John Wilson tries to convince Hester to reveal the name of the seducer but she is adamant. After Wilson, a young pastor Dimmesdale comes to her, but his voice is trembling and he looks as if he is ready to faint. He also asks her to reveal the name of the sinner, but the young woman looks past him, stubbornly keeping silent and holding her baby tightly to her chest.
When Hester returns to the prison, her husband, now calling himself Roger Chillingworth, comes to visit her. First of all he calms the child than gives the medicine to Hester. The woman is afraid of poison but he assures her that he came not for revenge on either her or her baby. He was blind to marry a woman so much younger than him and letting her go alone for two years. Hester was always honest to him and didn’t pretend to love him. So he has nothing to regret. But Chillingworth wants to know the name of a man who fathered the child and thus offended both him and her. Hester again refuses to say the name. Chillingworth forces her to swear that she will never reveal to anyone his real name and the fact he is her husband, saying to anyone interested that she is a widow. He decides to find out who is the father of Hester’s child and take revenge on him by all means possible.
After leaving the prison, Hester settles in an abandoned house on the outskirts of Boston and becomes a seamstress. Her embroidery is so beautiful that she quickly gets clientele amongst the richest people of the city. They just pretend to not know that their dresses and suits are embroidered and sewn by an adulteress. Despite her good income, Hester herself lives a modest life, buying only what she needs and giving the rest to the poor and sick people. She still hears insults far more often than the words of gratitude, but the woman is as stubborn as she was on the main square, silently doing what she feels right.
Her daughter Pearl is a beautiful but short-tempered and passionate girl. Hester doesn’t have an easy time with her as a single mom: Pearl just doesn’t want to obey any rules. She also feels that both she and her mother are for some reason rejected by the rest of the society. It affects Pearl deeply and she distances herself from other children not playing with them. The locals, seeing her strange behaviour and still unable to find out who her father is, call her a devilspawn.
One day Hester has to take Pearl with her to give the embroidered gloves to the governor. The governor isn’t at home so she waits for him in the hall. The man returns with two priests: Wilson and Dimmesdale. He says that Pearl should be taken away from her mother and raised in the strict obedience to Christianity as the child of sin. Pastor Wilson notices Pearl and decides to test her asking the girl if she knows who created her. Pearl, as confident as her mother, replies that no one created her, her mother just found her in rose bushes near the prison. Wilson is horrified: the girl is three-year-old already and she doesn’t know the very basics of Christianity. Moreover, she seems to be too smart for her age and doesn’t fear to express her thoughts to adults. He and the governor now are sure that Pearl should be taken away as soon as possible. Hester manages to save her daughter only because of Dimmesdale asking Wilson to give her a chance.
Meanwhile, Dr. Chillingworth also becomes well-known in Boston due to his knowledge of medicine and science. Soon after his arrival, he starts to pursue Dimmesdale, pretending to be a pious Christian seeking for the spiritual guidance. But the truth is that he is almost sure that Dimmesdale is the father of little Pearl.
All the Boston people are deeply worried about Dimmesdale, because his health has deteriorated drastically in recent years, right after Hester was condemned. So it was just natural for them to insist Dimmesdale seeks medical assistance from the best doctor in the city, Dr. Chillingworth. As a result, the young priest and the old doctor befriended each other and even settled together. But If Dimmesdale suffers the problems with physical health, Chillingworth mental health is also in danger now. He is so close to his offender now and all his thoughts are occupied with the single feeling: revenge. But to have it, Chillingworth needs to have the adamant proofs of the priest’s guilt. Feeling the ardent nature of Dimmesdale he wants to see the hidden depths of his soul and will not stop at nothing for it.
Chillingworth provokes the priest all the time, telling him the stories of the unrepentant sinners who died from nervous exhaustion. He claims that there is a spiritual wound that stays behind the physical disease and the pain that Dimmesdale endures is just a symptom of his suffering soul. But Dimmesdale replies that no one, even his friend, have the right to stand in between the sufferer and his Lord.
One day the young priest falls asleep in his armchair and doesn’t wake up even when Chillingworth enters the room. The old man approaches him, puts his hand on Dimmesdale’s chest and unfastens the clothes that the young man never took off in his presence. Chillingworth feels a strange and dark triumph: he is sure that he has just found what he searched for so long. Dimmesdale wakes up immediately and feels disgusted, but still he tries to convince himself that he has to find pity and patience for the lonely old man. But Chillingworth, as a doctor, now knows that Dimmesdale’s days are numbered and enough stress will cause a fatal heart attack. So now his task is to provide him with necessary stress.
One night Dimmesdale goes to the main square and stands where Hester stood years before. At the dawn, he sees Hester and Pearl and calls them. Both the woman and her daughter come and stand next to him. Pearl asks Dimmesdale if he is going to stand with them tomorrow, but he replies that they will stand together before the face of God, but it isn’t the right time to show themselves together to the mortal people. Suddenly the dark sky is lightened, a meteor falls to Earth. All the three see Chillingworth, looking at them. Dimmesdale tells Hester that he feels an unspeakable horror in front of that man, but Hester, bound by her oath, doesn’t reveal to him the secret of Chillingworth.
Years pass. Pearl is seven years old now. Hester’s chastity and kindness make the townsfolk treat her with a respect of some kind. Even the scarlet letter now looks not as a symbol of sin to them but rather as mark of inner strength. One day while walking with Pearl Hester meets Chillingworth and is shocked with the changes that happened to him in recent years. The calm and wise face of the scientist changed its expression to cruel and predatory and his smile looks more like a grin. Hester talks to him. It is their first conversation since the one they had in prison. She asks him not to torment Dimmesdale anymore saying that he condemns the priest to the fate worse than death. In addition, he suffers in front of his enemy not even knowing who he is. Hester asks why Chillingworth doesn’t take his revenge on her. He replies that he finds her punishment - the scarlet letter - enough. Hester begs him to think about God and salvation. She says that hatred turned him from a wise man to a monster, possessed by the devil. But Chillingworth is unable to forgive anymore.
Desperate, Hester decides to tell Dimmesdale that Chillingworth is her husband. She asks the priest to meet her in the forest. Dimmesdale confesses to her that he suffers so much because everything considers him to be pure while he tarnished himself so much. He feels an empty shell, a liar.
Hester tells him the story of Chillingworth. Dimmesdale is furious: he was suffering so much in front of the someone who secretly mocked and tormented him! But finally he forgives Hester and both of them agree that Chillingworth’s sin is much greater than theirs because he totally destroyed everything good he had in his soul for the sake of pure revenge. They understand that he will not calm down. Hester offers Dimmesdale to flee and start a new life. She talks to the captain of a vessel that soon will sail from Bristol and the captain agrees to take the family onboard.
The ship shall sail after three days and on the second day Dimmesdale is going to read a sermon. But he feels very uneasy and confused. Chillingworth offers him help but the priest refuses. The people gather in the main square to hear Dimmesdale’s words. Hester meets a captain of their vessel in the crowd and he tells her that Chillingworth is going to sail with them. She sees her husband looking at her and grinning ominously.
Dimmesdale’s sermon is outstanding and sincere. The festival begins, but the priest, unable to keep his secret anymore, decides to confess to people. Chillingworth, realizing that it will disrupt his plans and feeling that his victim is about to be forgiven by people and thus escape, rushes to the priest begging him not to shame himself. But Dimmesdale ignores him and asks Hester to come and stand near him. He repents of his sin aloud and, as a conclusion, he tears his cloth, exposing his chest. His eyes fade and Dimmesdale dies in Hester’s hands with the prayer as his last words. The rumors say that there was a scarlet letter burned on his chest, the same as on Hester’s dress. Others claim that his skin was clean but he just knew he is about to die and wanted Hester to be with him in his last moments, cleaning her of her sin.
After Dimmesdale’s death, Chillingworth loses all the drive and meaning of life. His spiritual and physical strength leave him at once and he dies within a year. His only heiress is Pearl. After the death of the old doctor Hester and her daughter disappear and her story becomes a city legend. After many years, Hester returns and voluntarily puts the emblem of her shame on her chest again, living in the same house on the outskirts of Boston. Pearl, apparently happily married, remembers about her mother, writes letters to her and sends gifts. But Hester prefers to live alone in the place she was happy with Dimmesdale once. She believes that she can be redeemed as he was.
Hester was buried near the grave of Dimmesdale, but even in death they are not allowed to be together - the graves were deliberately separated one from another.