2x04 Children Shouldn't Play with Dead Things

As they bury their father's dog tags at their mother's grave, the brothers' suspicions are aroused when they notice dead plants over the nearby grave of the recently deceased young woman Angela Mason (Tamara Feldman). They soon discover that the woman's cheating boyfriend was murdered the previous night. Sam and Dean dig up her grave and find the coffin empty. They deduce that her close friend Neil (Christopher Jacot), who was secretly in love with her, resurrected her as a zombie. Having killed her boyfriend, her next target is her roommate, with whom her boyfriend had been cheating. However, Sam and Dean save the woman and kill the zombie with a silver stake. Dean later apologizes to Sam for his recent behavior, and reveals he has had trouble coping with his guilt over their father's death.