The BAU investigates a spooky local ghost story of the 'Tall Man' and the clues it provides when two people go missing in the woods of East Allegheny's Dead Man's Conservatory, and a third mysteriously surfaces the following day with limited details as to what happened to her friends. To assist with the case, JJ reluctantly returns to her hometown, triggering emotional flashbacks to age 11 and her older sister's tragic death.