Sixteen-year-old Buffy Summers has moved to Sunnydale from L.A., hoping to leave Buffy's troubled past behind. But Sunnydale High librarian Rupert Giles knows who Buffy is: she is the Slayer, the one girl in all the world with the strength and skill to hunt and kill vampires. He knows about her past because he is her new Watcher -- the person whose destiny it is to train and guide Slayers on their path. Buffy quickly makes two friends: the shy, bookish Willow, and the goofy but lovable Xander, who is instantly attracted to Buffy.

When a student is found dead in a locker -- with bite marks on his neck and completely drained of his blood -- Giles enlists Buffy's help. She resists, trying to get out of the slaying game for good, but Giles insists that a crucial mystical upheaval is about to occur. Unbeknownst to them, a bewildered Xander overhears their conversation -- Buffy's secret is out. Later, in a dark, eerie chamber, we see a vampire who seems to be confirming Giles' prophecy. The vampire, Luke, kneels in front of a pool of blood and says, "The sleeper will awaken. And the world will bleed."

On her way to the Bronze, Sunnydale's hippest (and only) club, Buffy is followed by a handsome, mysterious stranger. He tells her she must be ready for the Harvest, and gives her a small cross. Giles meets her at the Bronze and she tells him about the encounter. Giles convinces her to use her power, and wants her to try to sense if there are any vampires in the room. She does sense one and finds him talking to Willow, but the two have walked away. Trying to catch him unawares, she grabs a makeshift stake, turns a corner and attacks... Cordelia, the snootiest girl in school, who already thought Buffy was a loser for hanging with Willow, and now thinks sheís certifiable. We see Jesse, Xander's buddy, chatting with a girl we saw in vampire garb earlier, but who now appears as a normal student, Darla. Back to the pool of blood, something breaks through the surface and rises: the demonic Master Vampire. He is hungry and weak, and asks Luke to bring him something young.

Outside the Bronze, Buffy enlists Xander's help in finding Willow, who's already been lead to a mausoleum by the vampire. Willow's happy to find Jesse there, until she sees that Darla has already bit him in the neck. Buffy and Xander enter, and Buffy promptly kills the vampire boy. Now Willow is finally in on the secret. While Darla tries to attack Buffy, Xander and Willow lead a weakened Jesse out. Luke joins the battle and throws Buffy across the room. As he tries to bite her in the neck, he burns his hand on her cross, giving her a chance to escape. She finds her friends struggling with several vampires. Buffy impales one and the others flee. Meanwhile, Jesse has been taken to the Master, who hears about Buffy. By her strength, he can tell that she's the Slayer. The Master knows that Buffy will come looking for Jesse, and then she will be his.

Giles enlists Willow to check the internet for more information about the Harvest, while Buffy decides to go look for Jesse. At the mausoleum, she runs into the stranger again, whose name is Angel. He warns that the Harvest will be that night. Then Buffy is shocked to find Xander has followed her. They find Jesse, who tries to lead them out, until he turns to face them and they discover he's become a vampire. More vampires surround and chase them, but they manage to escape to the street through a grating. The Master is furious that the Slayer has escaped. But he allows Luke to feed from him as a way of gaining strength for himself. He dabs some of his blood on Luke's forehead and paints a three-pointed star.

Willow's research explains that on the night of the Harvest, the Master Vampire can draw power from one of his minions while it feeds and then can break through from their reality to ours. The minion is called the Vessel, and bears the symbol we saw painted on Luke. Xander guesses the vampires will converge on the Bronze, since it's always filled with young people. That night, a newly confident Jesse strides into the Bronze and hits on Cordelia, who actually allows the former loser to dance with her. Soon, a gang of vampires takes over the club, with Luke at the helm. By the time Buffy, Giles, Xander and Willow get there, the suckfest is in full swing, with the Master gaining strength from each victim. Buffy manages to kill a few other vampires, then Jesse winds up impaling himself on a stake a frightened Xander was holding. Buffy breaks a large window, trying to make Luke think the streetlight is daylight, which will destroy him. He buys it for a second, and she takes advantage of his confusion by driving a stake through his back. Now the Master is too weak to break through to the other side, and Sunnydale has been spared. This time.