All Dogs Go To Heaven

Now King of Hell, Crowley appears before Sam and Dean and offers them a deal: an alpha in exchange for Sam's soul. The boys reluctantly agree and Crowley gives them their first case – the murder of a businessman in Buffalo, New York that appears to have been the work of a werewolf.

Arriving in Buffalo following another murder, the brothers finds a link between the murders to a man called Cal Carrigan. They interview Cal and meet his girlfriend Mandy, Mandy's son Aiden and their dog Lucky. Later, Sam and Dean spy on Cal in case he turns into a werewolf, but Cal is killed by Lucky who then secretly transforms into a man before returning to Mandy as a dog.

Later, Sam sees Lucky’s transformation and gives him chase, but Lucky is hit by a van, and is taking away by the occupants before Sam can stop them. Realising Lucky is not a werewolf, but a skin-walker - who can infect people with a bite - Sam and Dean track Lucky down to an animal hospital.

Under duress, Lucky tells the brothers that he was recruited and transformed into a skin-walker by a pack leader and told to wait for a command to bite and infect the family. Sam and Dean then force Lucky to help them stop the pack leader before he can unleash his deadly plan on the entire world.

Dean tries to take the leader out with a sniper rifle, but discover that Mandy and her son have been taken captive and that Lucky has been told to bite them. A shootout ensues, resulting in all of the skin-walker pack being killed.

The episode ends with Lucky trying to thank Mandy, only to be told to stay away...

Sam is still Dean's brother and he's going to prove it. Check out the trailer for the next Supernatural episode, All Dogs Go To Heaven.