The Master, displeased that Buffy is killing his vampires, sends a trio of warrior vampires called "The Three" after her. The Three ambush Buffy on her way home from the Bronze, but Angel arrives to help her. Angel is injured during the fight and Buffy invites him back to her house to dress his wounds and provide a safe place for him to sleep. Angel reveals his family was killed by vampires, leaving Buffy to theorize that hunting vampires is some kind of "vengeance gig" for him. Back at the Hellmouth, the Master allows Darla to execute The Three for failing their mission, as an object lesson in the use of power for Collin, The Anointed One.
The next day, after school and weapons training, Buffy returns to Angel, still hiding in her room. She notices her diary askew and, suddenly very agitated, begins to explain away entries that reveal her crush on Angel. Angel swears he didn't read it, and confesses his attraction towards her. They take that last half-step toward each other, and their kiss â at first hesitant and sweet â grows heated and passionate. Suddenly, Angel pulls back with a snarl of distress and Buffy sees his vampiric visage for the first time. She screams in shock and Angel dives out the window.
Giles researches Angel's history and notices the peculiarity that even though previously well-known as the vicious killer Angelus, Angel has shunned the company of other vampires since coming to America and has completely stopped preying on humans. Meanwhile, deep in the Master's lair, Darla insists that she be allowed to kill Buffy, using Angel as her weapon. Later that evening in the library, Willow is having a hard time tutoring Buffy in the history of the Civil War, since they are both distracted by gloom over boys â Buffy because she doesn't want to slay Angel and Willow because she wants to attract Xander.
Darla cons Buffy's mother into inviting her in by claiming to be yet another study buddy of Buffy's. Prowling around Buffy's house himself, Angel hears Joyce's cry and rushes in as Darla begins to drink. Daring him to drink too, Darla shoves the now unconscious Joyce into Angel's arms and escapes out the back door. Deeply tempted by Joyce's warm blood, Angel helplessly vamps, but resists the impulse to drink long enough to be discovered, in flagrantÃ©, by the returning Buffy. Horrified to find Angel apparently feeding from her mother, Buffy throws him out of the house, then calls for an ambulance. At the hospital, "anemic" Joyce tries to reconstruct events; her last memory is of inviting Buffy's "study friend" inside. Buffy misunderstands, thinking Joyce means Angel rather than Darla, and storms out to kill him.
Meanwhile, Giles talks further with Joyce and learns enough to realize that it was Darla, not Angel, who bit Buffy's mom. With Xander and Willow in tow, he rushes to find Buffy to warn her of the trap. Buffy tracks Angel to the deserted Bronze and demands an explanation; Angel recounts highlights from his Angelus days, then tells how he was cursed by Gypsies with a soul that would eternally wrack him with guilt for the atrocities he had performed as a vampire. He denies biting Joyce, yet confesses wanting to, as well as wanting to kill Buffy herself. The Slayer lays aside her crossbow and slowly offers her throat to him. Suddenly, Darla emerges from the shadows with a pair of handguns, boasting to Buffy that she had turned Angel all those centuries ago. Hearing gunfire, Giles, Willow and Xander rush in and distract Darla, shouting to Buffy that it was Darla who bit Joyce, not Angel. Looming up from behind, Angel stakes Darla through the heart, dusting his sire.
In their Hellmouth lair, Collin consoles the Master for his loss of Darla at Angel's hands. Spying Angel across the crowded room at the Bronze, Buffy goes to thank him - and to tell him goodbye. Helpless in the heat of their burgeoning passion for one another, their banter trails to silence and they deeply kiss one last time. As she reluctantly pulls away, Buffy doesn't notice that the cross she's wearing - the one Angel gave her weeks ago at their first meeting - was scorching his chest.