Castiel, a newly fallen angel, is asked by Balthazar and Gabriel to help retrieve the weapons of Heaven they had hidden. Posing as a high school student, Castiel does so faithfully, though is distracted by the brilliant Dean Winchester, a young hunter who's soul caught his eye while he was still in Heaven, who is determined to stop a mystery thief at all costs.

Much to Sherlock's surprise, John decides to bring home a kitten.

"Kittens, John," Sherlock says. "Kittens."