Supernatural is a paranormal horror tv series that follows brothers Sam and Dean Winchester as they travel around America hunting monsters and demons. The bloody, beating heart of the show is the close but tortured relationship between the brothers.
1—In the Beginning
Supernatural begins with two deaths—that of Sam and Dean’s mom many years ago, and with Sam’s girlfriend in the present. Both end up pinned to a ceiling and catching fire. This should give you a good indication of if you can handle this show’s level of gore and violence. From there, the boys head off to find their father, who recently disappeared, and discover a demonic conspiracy.
2—Then the Angels Show Up
A few seasons in, the angels show up, in particular Castiel, who eventually becomes a series regular. Once Heaven gets involved, things go from bad to Apocalyptic, and I am not being hyperbolic. See the TVTropes page The World is Always Doomed.
3—Things That Go Bump in the Night
The thing Supernatural does best—aside from the relationship between Sam and Dean—is its spooky, creepy atmosphere and monsters. It never fails to scare. This is very much a horror show and they rarely pull their punches. Most of the show is taken up with individual episodes of the brothers fighting the monster of the week, often an urban legend in the first season, but also creatures from mythology. There’s also an overarching myth-arc and episodes throughout a season vary between the two.
Although I loved the show for a long time, I’ve just had enough. So I wish well to all the fans who continue to follow the Winchesters’ adventures (there are thirteen seasons as of this writing and no signs that the show is going to stop), and to all the fans who are just meeting them.