Season 7 one-shot: Dean is torn after Cas' death, and resorts to drinking and using Cas' scavenged trench coat as an anchor to reality. Three weeks after the incident, however, Dean's over-excessive drinking takes a turn for the worst.

Robert Singer goes to London upon being contacted by his old partner. Days later Dean receives a distress call from Bobby, and in an effort to find him, he and Sam travel to London as well. In an unforeseen turn of events, they become acquainted with John Watson and Sherlock Holmes, two men who are investigating the mysterious disappearances of several men and women in the city.

After Lucifer's defeat, the remainder of Sam's powers and visions came to an end. A few months later, Sam wakes up from a terrifyingly vivid dream; one of a man committing suicide. The hunter doesn't pay it any mind until he has forms of the same nightmare every night. Sam soon learns through his premonitions that Lucifer had escaped, and is roaming among the living once again.

A strange form of the influenza is spreading around London. When assigned an especially interesting case, Sherlock is determined to get to the bottom of it. As Sherlock continues to work on the case, John notices that Sherlock seems much paler than usual and is receiving strange scabs along his arms and legs. Will John save Sherlock before it's too late?