9x17 Mother's Little Helper

Dean struggles with the after effects of the Mark of Cain. Meanwhile, Sam hears about a case where straight-laced people are turning into violent murderers. Sam suspects possession and suggests to Dean that they investigate, but Dean tells him to go without him. While interviewing the local townsfolk, Sam meets an elderly woman named Julia, who tells him the Men of Letters came to town in 1958. Julia tells Sam the story of a young man named Henry Winchester and his female companion, Josie Sands. While Sam is away, Crowley tests Dean.