Season 3, Episode 13: "This Is a Dark Ride"
How could you forget this episode? It takes place on a Halloween train ride and Adam Lambert performs, but that's just the beginning of the craziness. Officer Garrett Reynolds (Yani Gellman), who was dating Jenna Marshall (Tammin Sursok), is discovered dead. Worse yet, it's Aria who finds his corpse . . . while she's trapped in a box with him. As one of the most iconic Halloween episodes of this eerie series, you won't be let down!