[[Crowley]] approaches Dean and Sam with a job. When Dean is reluctant to listen to him, Crowley reminds him that he owns Sam and can send him back to hell at any time; on the other hand, if they play along and manage to bring him an [[Alpha]], Crowley will give Sam back his soul. Though reluctant to work for Crowley, they don't see any other choice.
He sends Dean and Sam to Buffalo, New York to investigate what appears to be a [[werewolf]] attack. When they arrive, they learn about another attack--so far, both a landlord (Erik Gieszelmann) and a dockworker (Ronald Garrigan) have been found with their chests ripped open and their hearts missing. Sam does some research and discovers what the two men have in common: [[Cal Garrigan]]. If anyone threatens Cal, they end up dead. They follow him and wait for him to turn into a werewolf, but an entire night passes without him changing. Then, when Cal is murdered in the same fashion as the other victims, their next suspect is Cal's girlfriend, [[Mandy]]. Sam is ready to take her in, but Dean is reluctant to capture and take her to Crowley without being sure of her culpability. He goes to see the scene of Cal's murder and do some more research while Sam keeps watch on Cal and Mandy's house. Although Dean doesn't find anything, Sam sees the family dog, [[Lucky]], change into a man, put on clothes, and leave the house.
Sam follows him and sees him talk to another man in a park. When he approaches, though, the man smells him, turns back into Lucky, and tries to run. Before Sam can catch up to him, Lucky is hit by a car and the driver loads him into the back to take him to an animal shelter. Sam, based on information from [[Bobby]], calls Dean and tells him that they are dealing with a [[skinwalker]] posing as a dog.
* [[Cal Garrigan]]
* Aiden Duran