Supernatural (2005)

S2E17 Heart

In the episode titled "Heart," Sam and Dean delve into a grisly murder case that leads them to uncover the identity of the perpetrator—a lycanthrope, or werewolf. As they piece together the clues surrounding the brutal killing, the brothers must confront the reality of a creature that transforms under the full moon, challenging their understanding of good and evil in their quest for justice.