While investigating a mysterious death in Chicago, Sam and Dean run into Meg, who is thrilled to see Sam again. The brothers soon discover Meg is behind the murders and attempt to catch her. Unfortunately, Meg is one step ahead of them and unleashes shadow spirits on the brothers to ambush them. Sam and Dean realize the trap isn't for them, but for their father.

Sam and Dean investigate a small town in Wisconsin where children are falling into comas for no apparent reason. The brothers discover that a witch is creeping into the bedrooms of the children and stealing their life force. While battling the witch, Dean recalls a past mistake that almost cost Sam his life at the hands of the very same witch, an event which has fueled Dean's protectiveness over Sam and his blind obedience to his father.