‘Pretty Little Liars’ Season 4 Spoilers: The Liars Investigate Ali’s Grave And Discover Sara Harvey In 'Who's In The Box?' [VIDEO]

The "Liars" discover that Sara Harvey is the girl behind Alison's mysterious grave, watch a sneak peek clip from the winter premiere episode "Who's In The Box?" prettylittleliars.alloyenterta

While Caleb is away, Hanna will research?! Well something like that, it seems that with Caleb away in Ravenswood, Hanna has more time to investigate the mystery of Ali's grave. "Pretty Little Liars" fans still have a couple of weeks until the show returns for Season 4B on January 7, but luckily we have a few juicy spoilers to hold you over for the Christmas season. A new sneak peek video picks up where we left off; the Halloween episode "Grave New World" shocked fans when Alison was revealed not only to be alive, but also to be the elusive Red Coat. Aria, Hanna, Spencer and Emily were just as shocked as fans to see that their once fearless leader was not dead, however the reunion between the former best friends wasn't exactly a happy one. Alison seemingly disappeared as quickly as she arrived and admitted that she was still on the run from someone. So while fans learned that Ali was still alive, the revelation opened nearly as many doors as it closed, specifically like who exactly is buried in Ali's grave?

E! Online has released a new sneak peek video, and it seems like Hanna is hot on the trail of whoever was buried in Alison's grave in the winter premiere episode, "Who's In The Box?" In the video, Hanna, Emily and Spencer are all together in what seems to be a classroom in Rosewood High, she then pulls out her laptop and begins to explain that she has been researching some stuff about Ali's mysterious grave. The normally ditzy Hanna looks serious as she explains that she found a girl in a nearby town called Cortland named Sara Harvey, like Alison she is the same age, blonde, petite and conveniently went missing around the same time as their friend. "Her parents think she ran off with a boy," Hanna tells Emily and Spencer as they look over the "Help Find Sara" website.

Emily asks how exactly Hanna picked Sara Harvey. "Well, I narrowed it down," Hanna says, getting defensive. "I mean she is sort of Ali's size. The timing is right and it's not too far away. While fans may be convinced, Spencer and Emily aren't ready to hop on board with Hanna's recent discovery. They both explain that Alison never mentioned Cortland, but as the Liars and fans know, there was a lot about Alison that she never mentioned. As the three girls continue to deliberate the possibility of Sara being in Alison's grave, A interrupts them with a message all her own. In the seemingly empty classroom, a vintage black and white movie starts to play on the projector, at the end of the creepy clip, a chalkboard shows a teasing message from "A," it reads "Ali, Ali, Oxen-free. Whoever finds her gets to keep her. Kisses - A." Here we go again! Be sure to tune in to Season 4B of "Pretty Little Liars" when it returns on January 7 with the winter premiere episode, "Who's in the Box?"