Buffy Summers is a slayer. She learnt about her destiny when she was 15. Her first watcher, Merrick, was from the watchers councill and soon got killed.
After that, Buffy got expelled from her old school for burning down the gym. She moved to Sunnydale and befriended Willow, Xander and Cordelia. She met her new watcher, English Rupert Giles in the first episode.
This slayer is unusual. She is the only one that has ever had a band of friends (the slayerettes or scooby gang) to help her rid the world from evil.
The current evil in Sunnydale is the master, hundreds of years old, he sired Darla, Angel's sire. Stuck in an underground cave, he waits for his time to come again. And it does, when Giles finds a book predicting Bufyy's death at the hands of the master. Buffy find out and can't deal well at first, but then she goes underground with her crossbow. She finds the master there, and he bites her in the neck, then drops her in a pool of water. Xander finds her and uses CPR and she is ressurected. She decides to take the master down, and just as the hellmouth is opening, she takes him by suprise and hurls him into the hellmouth.
In season 1 she met mysterious guy Angel, who is a vampire with a soul. Despite this, the two fell in love, finally consummating their relationship in season two. But when he wakes up Angel feels rather strange...he has turned back into Angelus, a vicious killer vampire who he was before he lost his soul. One moment of happiness and he would lose it again. He joins with Spike and Drucilla, two vampires from his past, and prepares to bring about the end of the world. But Buffy has to kill him to stop the ritual, and just as she is about to do it, Willow curses Angel with a soul again. Buffy kisses him passionately, then runs him through with a sword. buffy is heartbroken, and gets a bus out of town, not wanting to deal with the consequences. But she has to take up her role as the slayer again, and she returns to Sunnydale.
In season 3 Angel appears from hell after centuries of torture. With Buffy's help he turns back into what he was before, some ressemblence of a human life. Just before the mayor's ascention, Faith stabs Angel with a poisoned arrow. Buffy gets seriously angry and stabs Faith because the poison can only be cured by a slayer's blood. Only Faith falls onto the back of a lorry and denies Buffy her blood, so Buffy forces Angel to drink from her. She comes round in time to stop the mayor. Angel helps stop the Mayor, then goes to L.A. to live a separate life from Buffy, breaking her heart once more.
In season 4 Buffy mopes at college, has an accidental one-night-stand with Parker, and finally meets psychology T.A. Riley Finn and they become a couple.
She finds out, from the source of Spike, that Riley is part of a secret organization called The Initiative; who captures vamps and demons and makes them harmless. Maggie Walsh, psychology teacher is the head of the team, but her intentions are something more. Her creation, Adam is a human-demon-metal hybrid who kills Maggie before she can program him. Buffy finds him and she can barley hurt him.
Giles finds a spell which calls on the first slayer and imbunes Buffy with his brain, Willows spirit, and Xanders heart. She defeates Adam. But then the first slayer tries to murder the scoobies in their dreams and leaves cryptic messages predicting whats to come.
Season 5 comes and Buffy has a sister, Dawn who is 14. But her sister is not all she seems. She is the Key. She has the power to destroy the world.
Spike keeps having dreams about Buffy, finally realizing that he loves her. He declares his love to Buffy and she pushes away, revolted.
Riley, Buffy's current boyfriend thinks she's pushing him away. He provides her with an ultimun- he will leave unless she gives him a reason to stay. Buffy rushes to him but not in time- he leaves.
More pain comes when Buffy's mom goes into hospital with a brain tumor and dies. Buffy, Dawn and the scoobies find it hard to deal, even Anya who's been around for thousands of years.
God Glory wants to capture Dawn, to help her go back to her demon dimension. If Gory succeeds, Dawn will die and the earth will crumble. Buffy and the scooby gang fight Glory with all their might, but she starts the ritual that will destroy the world.
The only way to stop the world dying is for Dawn or Buffy to jump into a portal because their blood is the same. Buffy tells Dawn not to jump, gives her a message to give to the others, and dives off the bridge. Buffy is dead.
But not for long. Her friends, seeing that she didn't die a natural death, bring her back with Willow's witchy power. But what they didn't know was that she was in heaven. She says they can never know that at first but tells Spike the truth and tells her friends she was in hell. But when it's all song and dance in Sunnydale, she lets out her secret and is unhappy for such a long time after that.
It's even worse when Giles leaves Sunnydale, saying he's standing in Buffy's way to become an adult. For comfort over his departure, she sleeps with Spike and contines having a fling with him for a while, until she realizes she is using him.
She even has hallucinations where she is in a mental institution with her mother and father but with no Dawn and friends.
But when Buffy has to do her duty, she does it. Warran has killed Tara and Willow is seriously powerful, and after him. There is a showdown between Buffy and Willow, each seem equally powerful and kick each others asses, Willow maybe more so.
Buffy reconciles with Dawn, who had become a bit of a klepto and had been distancing herself from Buffy, but Buffy realizes she doesn't want to protect her, she wants to show her the world.