Supernatural The Complete 4th Season (2009)

After a mildly entertaining third season, Supernatural came roaring back with its best season yet. The show has also evolved in a number of ways. It is now more serialized. It is no longer only about two brothers driving around the country in Impala, with classic rock blasting, and fighting monster of the week. Episodes are more interconnected as the overall story revolves tightly around the coming battle between angels and demons.
The story also turns much darker as the two brothers struggle with inner demons: Sam's addiction to demon blood and power, and Dean's guilt over what he was driven to do in Hell. The two young actors have stepped up and met the demands of the roles, though the new actress for Ruby seems bland and out of place acting at opposite side of them.

The battle of angels and demons is no ordinary black and white affair. We learn that God is forever silent, and that some angels are shady and would not hesitate a second to sacrifice human lives for a "greater" cause. Lucifer was formerly an angel. "Fallen" angels may or may not be "evil" in Supernatural's universe. I marvel at how successfully the creator and writers of the show explore the Christian themes and myths. There are countless references to the Bible and Milton's Paradise Lost, and echoes of Philip Pullman's His Dark Materials. In so doing, the season goes beyond popular entertainment to the realm of serious fantasy.

I recommend anyone new to the series to watch the first three seasons, and then stay in sequence for season four. For long term fans of the show, watch the season again. It is that good!
The Complete Fourth Season