Amara (guest star Emily Swallows) unleashes a dark fog on a small town, causing everyone to go mad. Dean (Jensen Ackles) and Sam (Jared Padalecki) 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 (Rob Benedict) returns with an interesting proposal. Robert Singer directed the episode written by Robbie Thompson (#1120). Original airdate 5/4/2016.