I love this series. If you haven't seen it, you really need to start with Season 1 and work your way through. The show is now in its 11th year for a reason....it's GREAT! Sam and Dean Winchester are brothers, traveling the country and fighting demons. The series began with Dean as a young boy and Sam as a baby, when their mother was whisked away by a demon. Dad went demon hunting, Dean looked out for Sam, and the show began. The boys grew up and followed in Dad's footsteps. Even into the 11th year, there are still plenty of demons to fight and enough variety to keep it all interesting.
In Season 10, especially with the awesome blu ray clarity, Dean and Sam, along with Angel Castiel, continue to fight demons, while searching for a cure for Dean's Mark of Cain. Season 10 continues with the same quality as before. Crawley, Mama Witch Rowena, Metatron, and many others travel in and out of episodes. 23 episodes on 4 CDs provide many hours of scary entertainment, even a confrontation with Cain himself. The Winchester boys have also developed their own distinctive personalities.
Whether you believe in demons or not, this series is well done in a believable way in that the characters have emotions and display lots of "human qualities". Special features include: 3 episode commentaries, a memory share from seasons 1 - 9, a preview of season 10 from 2014 Comic-Con, behind the scenes for the 200th episode, (200 EPISODES and counting!), a piece on the Mark and the Blade (a special killing blade goes with the Mark), a piece on Supernatural fans, unaired scenes, and a gag reel.