One Last Party Favor is one of the better-known fansequels to Le Petit Four, itself a well-known sequel to the infamous fanfic, Cupcakes. The story begins with Twilight Sparkle researching a short string of bizarre disappearances. Spike is sent out to gather information, and notices suspicious happenings at Pinkie Pie's house. Pinkie Pie, believing that too much of her secret had been given away, gives Spike drugged food. He wakes up sometime later in a dark basement, and you know the drill. The story is here.