Elena Gilbert starts her senior year of school in the town of Fell’s Church with her friends, Meredith Sulez, Bonnie McCullough, Caroline Forbes, and Matt Honeycutt. Caroline promptly becomes competition with Elena for the position of most popular girl. A mysterious, handsome foreign boy named Stefan Salvatore, also enrolls. All of the girls within the entire school want his attention, but Stefan just brushes them off. This deeply shocks Elena, who has never been brushed off by a boy before. Stefan joins the high school football team with Matt and plays the position of wide receiver. Through flashbacks, we learn that Stefan is a vampire who was born in Renaissance Florence. There he fell in love with a German girl, Katherine von Swartzschild, who had been changed into a vampire by another vampire, Klaus, when she was ill and dying. Although Stefan hoped to marry Katherine, their romance became complicated when Stefan’s seductive older brother, Damon Salvatore, appeared. Although Katherine told Stefan that she loved him, she also seemed romantically interested in Damon. Katherine was almost an exact double of Elena. Vampires survive in sunlight when they wear lapis lazuli. Katherine has a ring of lapis lazuli and gold. Meanwhile, a number of mysterious and frightening events occur in Fell’s Church. A large crow exhibits un-birdlike behavior. Elena and her friends feel a threatening force that causes them to flee from the town’s old cemetery, and Elena loses her hair ribbon in the flight. A homeless man is attacked and partially drained of blood.
Stefan experiences fugue states and fears that he has been attacking people during them, even though he has no memory of doing so when he awakes. Elena devises various schemes to pursue Stefan, but Stefan continues to repeatedly avoids her. Stefan is magnetically and strongly drawn to Elena, she reminds him of his past and first love Katherine, and because of this, he is strongly tempted to drink her blood. Elena finally corners Stefan at the Homecoming Dance. She believes he will be unable to refuse her invitation to dance with her, the Homecoming Queen. However, Stefan’s date for the evening is Caroline, who foils Elena’s plan. To show she is not hurt, Elena leaves the dance with Tyler Smallwood and Dick Carter, two boys who are on the football team and who have shown themselves to be hostile to Stefan in the past. Another girl, Vickie Bennett, goes with them. The four go to the cemetery to deface the funerary statues of Honoria Fell and Thomas Fell. Elena perceives one statue moving and revealing an empty space beneath, but no one else shares her vision. A drunken Tyler sexually assaults Elena. Stefan appears and rescues Elena by beating up Tyler. Stefan takes her to his room at the boarding house so that she can clean up before he drives her home.
Elena confronts Stefan to ask why he’s been avoiding her. His responses are evasive, but they lock hands and then kiss, at which point Elena is completely certain that she’s found her other half and her romantic destiny. When Stefan drives Elena home, she learns that Vickie has been found wandering on the road, scratched and raving about having been attacked by some supernatural force. To Elena's confusion, Stefan then seems to draw away from her emotionally. The next day Stefan tries to break up with Elena, but she refuses to let him do so. Without his knowing, she opens a small casket on Stefan’s dresser and finds the hair ribbon she lost when fleeing from the cemetery the first week of school. This convinces her that he has secretly loved her from that time. She writes about the hair ribbon and the romance in her diary, also noting that Stefan still seems to be hiding something from her. Elena, Bonnie, and Meredith plan the school’s Haunted House for Halloween. The lights go off and a seductive college-aged boy enters. He nearly persuades Elena to kiss him despite her love for Stefan. When she refuses, he says he may finally have found the girl he’s been looking for.
Then he disappears. Elena brings her diary to a slumber party with Meredith and Bonnie. They hold a dumb supper at which Elena invites her future husband to enter Bonnie’s house. She does not see Stefan, but the seductive college-aged boy appears. He quotes love poetry and tries to kiss Elena. Elena’s head swims and she nearly succumbs, but she manages to resist. The boy reacts with anger but leaves when Elena asks him to do so. Elena then learns that Bonnie’s dog has unexpectedly died during the dumb supper and that her diary has been stolen. Over the next few weeks, Elena becomes more concerned at how Stefan seems to be drawing subtly away from her and keeping secrets. For example, he is wearing an object on a chain around his neck, hidden underneath his clothing, and he refuses to talk about it. He appears haunted and sad. Elena is determined to bring them back together and persuade Stefan to trust her completely. Because Stefan confronted their European History teacher, Mr. Tanner, on the first day of school and corrected him about how teenagers behaved during the Renaissance, Elena plans to wear a Renaissance ball gown as her Halloween costume. She believes this will overcome Stefan’s resistance to her. Much to her distress, however, Stefan’s reaction to seeing her in the dress is shock.
During the Haunted House, Mr. Tanner is given the role of Bloody Corpse. This requires him to be covered with fake blood with a knife lying nearby; he is supposed to sit up unexpectedly to frighten visitors. When Bonnie leads visitors to see the Bloody Corpse, however, she finds that Mr. Tanner actually is dead and covered with blood. A panic results. Tyler tells everyone that the murderer is probably Stefan Salvatore because the strange violence in Fell’s Church began at the time that Stefan arrived in town. This spurious logic turns the crowd into a mob. Elena passes a warning to Stefan through Matt, and Stefan flees back to the boarding house to prepare to leave Fell’s Church. Elena follows him and finds Stefan on the roof of the boarding house with blood smeared on his lips, his fangs extended, and dead birds at his feet. In her shock, she falls off the roof, but Stefan leaps after her and catches her in mid-descent. Elena is unhurt. Elena demands explanations at last. Stefan tells her he became a vampire when he and Damon both pressed Katherine to marry them. Katherine told them that she would make her choice between them, and that night she came to Stefan’s bed and turned him into a vampire. Stefan believed he had been chosen.
The next day, however, she told Stefan and Damon that she had gone to both their beds, drank both of their blood, and gave them both her blood. She gave each a ring and told them she expected they would all live happily ever after together. Stefan and Damon rejected Katherine’s plan and demanded that she choose between them. Katherine fled in tears. The next day, they found her empty dress in the garden and ashes in the dress. A note nearby told them that she had taken off her lapis lazuli ring to commit suicide and thereby bring the brothers back together. Distraught and blaming one another, Stefan and Damon then dueled with swords. Damon stabbed Stefan through the heart. When Stefan fell and Damon bent over him, Stefan stabbed Damon fatally. Both brothers were thereby locked permanently into their vampiric state. Stefan was buried with Katherine’s ring and beside Damon. When both woke, they separated in fear and confusion. Stefan lived on animal blood in the streets of Florence until Damon, who had become a powerful mercenary soldier, returned and threatened to kill him unless he left. They saw one another intermittently since that time, with Damon invariably threatening to kill Stefan.
Stefan also explains to Elena that vampires have Powers that include the ability to influence and read minds, the ability to turn into animals, and the ability to influence the weather. Damon drinks human blood and so is more Powerful than Stefan, who tries to lead a moral existence by drinking only animal blood. Lapis lazuli protects vampires from sunlight. The mysterious object Stefan wears on a chain around his neck is revealed to be Katherine’s ring. Elena assures a guilt-ridden Stefan that he is not responsible for Katherine’s death or Damon’s. She also persuades Stefan that he is not responsible for the violence in Fell’s Church as he had feared. She now is able to identify Damon as the seductive college-aged boy who nearly persuaded her to kiss him. Since Damon is in Fell’s Church and is evil, Elena concludes Damon must be responsible for the violence. He has not shown himself because he has been trying to make Stefan blame himself. Stefan finds Elena’s argument convincing.
Over Stefan’s objections, Elena then persuades Stefan to drink her blood in order to erase the last boundary between them. After returning Elena to her home, Stefan goes to the woods and uses his Power to call Damon, who appears. Damon admits to killing Mr. Tanner and tells Stefan that he must abandon Elena to Damon, who wants her for himself. Stefan refuses. Damon attacks Stefan and drinks his blood against his will, a process that is extremely painful. When Damon releases Stefan, Stefan attempts to stagger back to his car but is attacked again from behind, after which he falls unconscious. The next day Elena finds Stefan has disappeared. Furious and certain as to who should be blamed, she goes to the cemetery and shouts Damon’s name to summon him. Here, the book ends.