As a huge fan, I love this series. Here's a little plot summary I've found.

"22 years ago, John Winchester awoke in the middle of the night to find his wife, Mary, pinned to the ceiling, bleeding from the stomach, and set aflame. He managed to get his sons, 4-year-old Dean and six-month old Sam, out of the house, but Mary was killed leaving John devastated and determined for revenge against the supernatural creature that murdered her. Present day, John has raised his sons to fight supernatural forces. Demons, ghosts, even cryptologic creatures. However, they can't find the thing that killed Mary. With his constant clashes with his father, Sam becomes disenchanted with the hunter's lifestyle, and goes away to college, where he falls in love with a girl named Jessica Moore. After years of estrangement, Dean shows up at Sam and Jess' one night to ask for Sam's help to look for their father who had gone missing during a "hunting trip". At first, Sam is reluctant to be roped back into the world of hunting and prefers his "safe" normal life he had managed to make for himself with Jess, but when he finds Jess dead through the same M.O. as their mother, he sets out with Dean to find their father by following any supernatural leads they can find across the country, hoping they track him down."

This series always has something new happening, there's never a time when there's no action. I am on the 5th season, and I haven't seen a "filler" episode yet. "Myths" of the real world come to life in this series as every supernatural creature has they're weakness, special abilities, etc as Sam and Dean hunt all supernatural beings down.
I recommend this show to everyone.

Hey look a thing I watch.

Supernatural is good. Everyone should watch.