Supernatural Episode Details!

Episode 4x04 "Metamorphosis"

The boys are joined by an old hunter friend named Travis to fight a worm-like creature named "Rugaru." The monster, who takes over a character named Jack Montgomery, makes people extremely hungry, eventually makes them want to eat humans. The brothers discover that the only way to stop them is with fire. Later in the episode, the boys (accidentally?) try to set Jack's wife on fire. Seeking revenge, Jack kidnaps Dean and tries to eat him.

Episode 4x06 "Phoebia"

The boys fight a ghost named Luther. Luther was in love with a married woman named Jesse. After Jesse went missing, her husband, Frank, went after Luther and choked him with a chain. Frank was never arrested because of his prominent place in society. Sam and Dean try to figure out if Luther's spirit is involved with Frank's death before the spirit goes after others.

Episode 4x07 "Its the Great Pumpkin Sam Winchester!"

Sam and Dean meet Uriel, who is much more coarse and less friendly compared to Castiel. Sam disobeys orders from Uriel to not interfere with certain demons who attack both the brothers and the town, so Uriel threatens their lives. The boys also fight against witches named Tracy and Don and another person (spirit?) named Samhain.

Source: SpoilerFix