Sixteen-year-old Buffy Summers has moved to Sunnydale from L.A., hoping to leave her 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 she's 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 led to a mausoleum by the vampire, Thomas. 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 Thomas. 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. The episode ends with Buffy and company in peril and a “To be continued” on the screen.