Buffy Anne Summers is the Slayer, the chosen one. She finds this out living in L.A. and burns down a gym full of vampires at her old school. So she gets expelled for vandalism.

Buffy and her Mum move to Sunnydale and she goes to school on what turns out to be the mouth of hell. This is basically a demon magnet. She must go about her normal life, with all her love troubles and keep a whole other secret identity of slaying all kinds of demons, particularly vampires, when the sun goes down. And then sometimes in the day.

But she has lots of help from her friends.

She also gets helps from Angel, a vampire with a soul. They become friends and fall in love. But Angel is cursed, when he finds true happiness he losses his soul again and become Angelus...

Buffy and Angel decides they can't live together (curse) so Angel moves to L.A. and Buffy goes to college.

In college she meets Riley, who works for the Initiative ...