“Pretty Little Liars” fans are in for an early Christmas treat on Dec. 9. The ABC Family series will air its very first holiday special, and it’s certainly one that viewers won’t want to miss.

When we last left off at the Season 5 summer finale, Spencer (Troian Bellisario) had been accused of murdering Bethany Young, the teenage girl that ended up in Alison’s (Sasha Pieterse) grave. Arrested for the crime, the other Liars scrambled to find evidence to clear her name. After a recon mission at Radley Sanitarium, it was Mona (Janel Parrish) who found damning evidence against Alison … but she never got the chance to use it to free Spencer. In a shocking ending, “A” broke into the Vanderwaal house and murdered Mona before she could show Aria (Lucy Hale), Hanna (Ashley Benson), Emily (Shay Mitchell) and Ezra (Ian Harding) what she discovered.

As we previously reported, the holiday episode, titled “How the ‘A’ Stole Christmas,” will pick up after the summer finale events. The Liars will continue to try to gain evidence to help Spencer, all while devising a plan to “get justice for Mona and finally bring Alison down.”

“Pretty Little Liars” fans will have to watch the special in order to find out that plan, but we’ve got some scoop on other juicy plot lines – like ghosts. It sounds like the series may be ripping a page out of Charles Dickens’ “A Christmas Carol.” According to TV Line, Tuesday’s episode will feature “Mona’s ghostly return.” The site teased that even in death, Mona will have “a few surprises for Alison up her sleeve.”

“The real surprises are the one she offers to Alison, who finally gets to see things through Mona’s eyes,” executive producer Marlene King revealed to TV Line.

Does Alison feel guilty for her brutal exchanges with Mona over the years? And does this mean that Alison is not Mona’s killer? Viewers will have to wait and see, but no matter if Alison is innocent or not, her relationship with Emily has not changed. Although Emily has fought for Alison over the years, Alison's actions have caused Emily to lose trust in her old friend. The pair are on the outs, and it doesn't look like they'll mend their friendship (or more) anytime soon.

“Emily feels like she has been betrayed by Alison,” King told TV Guide. “That’s where we begin the episode and that’s very much a part of her story.”

The “Pretty Little Liars” Season 5 Christmas episode will air on ABC Family on Tuesday, Dec. 9 at 8 p.m. EST. What do you think will happen? Tweet your thoughts to @AmandaTVScoop.