The work is prefaced by the publisher's foreword (as Richardson calls himself), reminiscent of the heroes of previously published novels. "Pamela" - a testament to the benefits of virtue; “Clarissa” is an instruction to those parents who, through unreasonable compulsion, give rise to evil. Finally, “Grandison” is “the deeds of an elegant soul”, strictly following strict moral rules in all situations of life.

A lovely, orphaned young girl from a good family, Miss Harriet Byron, writes her relative Lucy Selby detailed letters about her stay in London with her cousin Archibald Reeves. The letters are not without coquetry, as the girl describes the characters, habits, and manners of all her admirers. Miss Harriet Byron's merits, her appearance, grace, and education (later it turns out that she is fluent in Italian) attract many fans. But neither nobility, nor wealth, nor attractive appearance are sufficient reasons for marriage. Harriet writes that the freedom granted to her by her relatives is too expensive to lose her in marriage. At the grandfather, it is obvious that the girl’s heart has not yet woken up for love. Miss Byron does not refuse visits, balls and other entertainments, as they amuse her. The only thing that has upset her lately is an unsuccessful fancy dress (which later nearly ruined her reputation with her absurdity), which she described in a letter to her friend.

Archibald Reeves enters into correspondence. He informs his relatives of Selby about a terrible misfortune. Harriet Byron was kidnapped when she returned from the masquerade. Suspicion falls on John Greville, the rejected contender for Miss Byron's hand. He promised to leave London after being refused, but secretly remained in the city, having moved to another apartment. Other abduction participants are later identified. Only a few days later the true circumstances of the incident are clarified. The Reeves family received a letter signed by Charlotte Grandison stating that the girl is in their house and is so weak that she is not even able to write with her own hand. Everyone is oppressed by the idea that a pretty girl could become a victim of violence. Fortunately, the circumstances were favorable and the honor of the girl did not suffer,

Cousin Reeves immediately goes to the Grandison's house and finds out the circumstances of the abduction from the man who saved Harriet Byron, Sir Charles Grandison. The true culprit of the abduction was the baronet, Sir Hargrave Polkofen. He also made an offer to Miss Byron, and, unlike John Greville, did not express his displeasure in any way, being rejected.

Sir Charles Grandison talks about the circumstances in which he met Harriet Byron. Returning from London, he saw a racing carriage and, deciding to avoid a collision, ordered his coachman to turn aside. But involuntarily blocked the approaching crew. When he stopped, Sir Charles heard a woman scream and saw a woman wrapped in a cloak in the carriage window. Noticing the emblem on the door of the crew, Sir Charles decided to find out what was the matter. The owner of the carriage replied rather rudely that he was taking his wife who had violated marital duty to his estate. The woman tried to escape from his hands and asked for help. Since the young lady claimed that she was not the wife of this gentleman, but was abducted by him, Sir Charles decided to intervene and free the lady from the hands of the rude gentleman. He kept silent about the details of this release and was very restrained in the story.

Later, from a letter from Harriet Byron to his girlfriend, Lucy Sedby, it becomes clear that Sir Charles was heroic. The story of her abduction was as follows. After the masquerade, the servants hired by a footman Wilson (who turned out to be an accomplice of the kidnapper) took the portchette (stretcher) not to Reeves' house, but to another part of London, to the house of a certain widow. There the unfortunate Miss Harriet was waiting for the villain Polksfen. The girl begged the kidnapper to let her go home, but he reminded her of how his pleas for marriage were rejected. Now, said the failed groom, he is married against the will of the girl. But he will do it as a noble person - in the presence of a priest.

Priests bribed by Polksphen appeared who did not want to listen to the girl's explanations. Only the presence of the widow, misled by the accomplice's accomplice Wilson (who promised to marry one of the widow's daughters), saved Miss Byron from coercion. When the priests left, the girl tried to jump out after Polkofen, who in a rage slammed the door so hard that Miss Byron was badly injured. He was afraid to leave the bleeding girl in London and decided to take his victim to his estate. On the way there, a meeting took place with the noble Sir Charles, who in his story kept silent about the danger that his own life was in. The enraged kidnapper first tried to squeeze the girl's mouth so that Sir Charles would not hear her screams, and then drew his sword against the noble gentleman. Sir Grandison managed to stop the kidnapper, dumping him with a single blow. And only after he told Polksphen's companions his name did he respectfully put Miss Byron into his carriage. Although Harriet describes in detail the details of his abduction in the letters, it was decided to hide from the acquaintances and the authorities everything that happened. Everyone who was interested in Miss Byron was informed of her malaise, which required her to leave London for a few days.

In subsequent letters, Harriet confesses to her friend that her letters can no longer be the same playfulness and can only be surprised at her own frivolity with which she described her admirers. Harriet reports in detail about the Grandison family - the charming Charlotte and her brother, Sir Charles, his graceful figure, delicate facial features, exquisite manners, but at the same time sheer strength and masculinity, without the slightest touch of dandy or gentleness. It is immediately evident that Sir Charles did not try to evade the weather or other vicissitudes awaiting travelers on the road. Grandison's kindness and compassion for all living things is so great that he forbids horses to cut their tails so that animals can brush off annoying insects.

Harriet talks about the parents of Charles and Charlotte Grandison. Their father was not an ideal husband, often went to London and was absent for a long time. Once he was brought seriously wounded after a duel. His wife was so deeply shocked that, leaving her husband, she soon died. A dying, unhappy woman asked her son not to participate in fights. The reader later learns that Sir Charles led a decent life and did not inherit his father's weaknesses, but to protect the weak, he always without hesitation bared his sword.

Miss Byron learns that her captor not only does not feel remorse, but dares to challenge Sir Charles to a duel. Despair embraces Harriet to such an extent that she is ready to sacrifice herself, so long as nothing threatens the life of Sir Charles. Her cousin Archibald and Lucy Selby have long noticed that the girl is not indifferent to her savior. Fortunately, it all ended very well and the duel that took place once again confirmed the incredible nobleness of Sir Charles.

Grandison did not shy away from the challenge to a duel and, having come to a meeting with Polksphen, tried to convince him that no one had the right to force a woman to marry, all the more by force. Outwardly calm, the villain invited Grandison into the garden, supposedly in order to say a few words in private. When the young men found themselves in the garden, Polksphen unexpectedly attempted to viciously attack Sir Charles from behind, but failed. Grandison easily threw the hapless adversary to the ground. Polksphen had to admit defeat. After meeting with Miss Byron, he vowed to leave England.

But the development of relations between Charles Grandison and Harriet Byron was hindered by a cordial secret, the key to which should be sought in Sir Charles's travels in Italy. Over time, Miss Byron learned all the circumstances of this story. Living in Rome, Sir Charles met with the offspring of a noble family who led a rather frivolous lifestyle. Grandison tried to distract Jerome della Poretta from frivolous acts, but failed. The young Marquis passionately fell in love with a lady whose beauty was the only virtue, and left after her from Rome. After some time, Sir Charles decided to go further, but on the way to Cremona the herds witnessed a terrible incident. The already defeated young man defended himself with difficulty from several attackers. Noble Sir Charles could not remain indifferent and rushed to the defense of the unfortunate. Naturally, he coped with the villains and only after that he discovered that the victim was Jerome della Poretta. It turns out that the lady’s fans were waiting for the opponent along with the hired killers.

Delivering a mortally wounded young man to Cremona, Grandison reported what had happened to his family. The whole family of Marquises della Poretta arrived from Bologna, and barely alive Jerome told his relatives how Sir Charles tried to keep him from rash actions, how bravely rushed to defend him from the attackers, with what caution he delivered him to the city. The raptured parents began to call Sir Charles their fourth son, and Jerome - his brother. All this could not but impress the only daughter of the Marques of Porett - Clementine. Since Sir Charles did not dare to leave his friend in serious condition, he settled in the house of Poretta. He read aloud, talked about England and finally finally conquered the heart of Clementine della Porega. The girl did not want to pay attention to anyone, not even Count Belvedere, sincerely carried away by a noble beauty.

Jerome della Poretta decided that Sir Charles should become his true brother by marrying Clementine. To do this, only one condition must be fulfilled - to become a Catholic. But it is precisely this that is an insurmountable obstacle for the noble Grandiose. His heart is free, he could sacrifice everything for the girl, but not faith. The whole family of della Poretta, including Jerome, feels offended, because Clementine belongs to the noblest and richest family in Italy.

The poor girl could not stand the incident and became seriously ill - she lost her mind. It could not utter a word and sat motionless, it could not find a place for itself and rushed about the room. She wrote endless letters to Sir Charles and did not notice that their relatives were taking them away. The only thing that awakened her to life was talking with an English companion. And she also liked to consider the map of England, recalling the noble Sir Charles. In moments of enlightenment, she insisted on a tonsure. But the Marquis della Poretta could not allow the only daughter of such a high-ranking family to imprison herself in the monastery.

Her parents decided to let her travel around the country so that she could recover. Clementine took advantage of this and left for England, the homeland of her unforgettable Grandiose.

This trip was favorable to her health. She did not interfere with the marriage of Sir Charles to Harriet. And over time, she recovered so much that she could agree to a marriage with Count Belvedere.

The novel concludes with a beautiful wedding for Miss Byron and Grandison. They settle in Grandison Hall and enjoy the magnificent nature.