Ep 4. Metamorphosis

In Supernatural season 4 episode 4, titled "Metamorphosis," the Winchester brothers, Sam and Dean, investigate a string of gruesome murders that all lead back to a man named Jack Montgomery. As they delve deeper into the case, they discover that Jack is a shape-shifter who is unable to control his urge to kill and transform into different people.

Meanwhile, the brothers are still dealing with the aftermath of Dean's deal with a demon to bring Sam back to life. Dean only has one year left before the demon comes to collect his debt, and he is desperately searching for a way to avoid his fate.

As the case unfolds, the brothers meet another hunter named Travis who has a personal vendetta against shape-shifters. He believes that they are all evil and must be eliminated, while the Winchester brothers try to take a more nuanced approach and find a way to save the innocent people who are caught up in Jack's rampage.

Sam, in particular, is drawn to Jack's struggle to control his transformations and empathizes with his plight. He sees shades of his own struggle with his demonic powers and is determined to find a way to help Jack without resorting to violence.

As the brothers race against time to capture Jack and find a way to break the curse that makes him a monster, they must also confront their own demons and come to terms with the price of their choices.

Overall, "Metamorphosis" is a tense and emotional episode that explores the complex themes of redemption, forgiveness, and humanity. The monster-of-the-week format allows the show to delve deeper into these themes while still delivering a thrilling and satisfying storyline. Fans of the series will not be disappointed by this installment, which showcases the best elements of Supernatural's storytelling and character development.