Seasons 1-7 rewatch.
The premise: Since the dawn of time, the world of humans has been stalked by the forces of evil, chiefly vampires and other demonic forces. The Slayer was created in the form of one teenaged girl and given the strength, toughness and skill to fight them. Whenever she is killed-and she is always killed, always- the power immediately passes to another girl. Few make it 18. Who inherits the mantle and where is neither determined nor known by man.
An age old organization, the Watchers, tries to locate potential Slayers worldwide and train them, with limited success.
Buffy Summers is the latest Slayer at age 16. She arrives in Sunnydale, California after being expelled from her old school for burning down the gym. Her parents have divorced and she lives with her mother. This was portrayed in the 1992 movie, which can be seen as a first draft version of the series concept. Buffy is officially and emphatically retired, having both been there and done that.
But Sunnydale, oddly, has a shockingly high unsolved murder and disappearance rate that, oddly, nobody talks about.
Seasons 1-5 are pretty phenomenal. Very few TV shows can have soul-shaking horror, LOL scenes of multi-layered humor that can reach back episodes or even seasons, shocking violence and scenes of transcendent courage...in one episode. Multiple times. Ever laughed with tears in your eyes, your hair standing on end shouting YES! and thinking OMG no?
There are a couple of dozen episodes like that in BTVS.
The 2 part Pilot establishes the characters and setting efficiently and sets up the lore. The rest of the short half season has mostly standalone "Monster of the Week" episodes and is a little uneven, campy and very funny...until suddenly it becomes Dark. Black. Serious.
The Angelus arc in the incredible season 2 became simply operatic in intensity. "When She Was Bad" is one of the better depictions of psychological combat trauma and "Passion" is a portrayal of sickening evil for its own sake, and the delight it brings. Buffy learning the true cost of being The Slayer is sobering and heart wrenching. Writing, acting and character development reach a pitch rarely achieved
Season 3, featuring the fall and corruption of Faith the Slayer by the Mayor(one of the most interesting villains ever) and their twistedly heartwarming father-daughter surrogate relationship is not to be missed. "Helpless" the episode where the Watcher's Council tests Buffy is brilliant. "The Wish" where an angry young woman is granted her wish of Buffy never coming to Sunnydale offers a grim look at the life of a Slayer without friends or family. Just a desperate soldier in an unending nightly war where the only release is death in battle.
Season 4 isn't as strong, but features the addition of Spike and Anya as permanent characters, has the epic dialogue free "Hush", and the reveal of the Initiative, the government anti-demon supersoldier program, pays off spectacularly. Plus, Buffy gets laid a lot.
Season 5 builds slowly as the new Big Bad turns up way too big and a confusing, desperate situation goes from bad to worse to Gotterdammerung. Buffy matures, ages and hardens as she embraces being The Slayer. There's a scene that hearkens back to season 1, where Buffy manages to kill 3 vampires in one night after prolonged fights. In this one, she kills 8 in about 5 merciless seconds. It was kind of...appalling.
Then there is "The Gift."
Season 6 is the weakest overall season with only a few standout episodes, particularly "Conversations With Dead People" and the hilarious, unsettling musical "Once More With Feeling" that has the most horrifying reveal...well, ever.
Season 7 is uneven at first, then finds its footing (after Buffy gets the brakes beat off her ass) and proceeds to a really clever culmination of the series about "The Chosen One. One girl in all the world."