Supernatural S11 E20 Don't Call Me Shurley

"Saving people, hunting things, the family business."

Amara unleashes a dark fog on a small town, causing everyone to go mad. Dean and Sam realize this is a stronger version of the original black vein virus Amara previously unleashed. They team up with the sheriff to protect the town but their old remedy no longer works. Meanwhile, Chuck returns with an interesting proposal.