Walden reconnects with Kate and is sure she’s “The One” – that is, until he meets Vivian (guest star Mila Kunis – That ‘70s Show, Black Swan), a beautiful, free-spirited world traveler who shows up on his doorstep. Feeling an instant connection with Vivian, he soon becomes convinced that she’s “The One.” Meanwhile, Alan and Gretchen grow closer.
Charlie's announcement that he is coming home for his birthday creates a difference of opinion among the Liars and members of the DiLaurentis family; Mona shuts out Mike; Hanna receives an unwanted surprise.
The girls try to clear Spencer's name as Christmas approaches in Rosewood; a ghostly presence shows Alison a glimpse of the past, present and future.