Trick or treat! “Pretty Little Liars” returns on Tuesday, Oct. 22, for a special Halloween episode that is bound to send shivers down your spine. Episode 13, “Grave New World,” will air on ABC Family at 8 p.m. as part of the network's “13 Nights Of Halloween,” but before you tune in let’s recap the drama that occurred during the summer finale.

[Click HERE to read a full synopsis for the “Pretty Little Liars” Halloween episode.]

1. Threats

Hanna’s mom had the charges against her dropped when Travis came through with information that the cops didn’t have. “A” threatened the Liars that “if she goes free you’ll hear from me,” and the girls realize that it’s now “World War A.”

However, Ashley’s not the only one in danger -- Emily, Hanna, Spencer and Aria receive a package from “A” and discover a children’s coffin with a doll of Mona inside. A text from “A” warns them that they need to get to Mona before the cops do … or the police will think that they killed her.

2. A New Suspect In Wilden’s Murder

After Ashley was cleared of Detective Wilden’s murder, they released a sketch of their new suspect: CeCe.

3. Wren/Melissa Conspiracy

Wren’s been acting suspicious lately and while no one knows what he’s up to, it’s obviously no good. Spencer tries to visit Wren at his apartment but he’s nowhere to be found. However, what Spencer doesn’t see is that Shauna is hiding inside his house.

Later on at the coffee shop Spencer watches as Shauna accidentally leaves behind some papers. The papers reveal that Wren is moving back in with his ex-fiancé … Spencer’s sister, Melissa.

4. A Trip To Ravenswood

Emily, Hanna, Spencer and Aria receive another package from “A” that contains a magic trick and a message that says, “Watch me make a girl disappear.” The message sends them to the town of Ravenswood where Charlemagne the magician is performing.

Pulling Aria out of the crowd for a “disappearing act,” the trick is that Aria’s not the one to disappear. Instead the girls find that “A” stole Emily while being distracted by Aria and Charlemange.

5. Emily’s Close Call

“A” took Emily and locked her in a box. But instead of burying the box, “A” put it on a conveyor belt towards a lumber mill saw. The girls find “Red Coat” and follow her to the mill where they’re able to help rescue Emily … with the help of “Red Coat.”

6. Two Red Coats

“Red Coat” hit the button stopping the saw from killing Emily and giving the girls a chance to help her out of the box. However “Red Coat” doesn’t stick around and the Liars discover that there is not one “Red Coat,” but “two.” Spencer follows the “Red Coat” that helped Emily while Aria chases after the “Red Coat” that more than likely locked Emily in the box. Using martial arts to fight back, Aria discovers that her “Red Coat” is CeCe. Their fight gets ugly and CeCe tries to escape by jumping on a rope. But the rope snaps, leading the girls to believe that CeCe is dead on the ground.

As for the other “Red Coat” that Spencer was chasing? Spencer believes that it’s Alison.

7. “A’s” Lair

“Red Coat” lead Spencer to “A’s” true lair. Inside the Liars discover how “A” has been keeping tabs on all their actions -- a complex computer system. After digging around they find that “A” started a corporation and has men’s jackets, leading them to speculate that “A” is actually a man rather than a woman.

8. Mrs. Grunwald’s Tale Of The Night Alison ‘Died’

Spencer met Mrs. Grunwald earlier in the season and denied knowing anything about Alison. However this time she tells the girls the truth – Alison was calling her the summer that she disappeared. “She was afraid,” Mrs. Grunwald tells the Liars. “And she was right to be.”

Mrs. Grunwald explains that she has the gift of insight and felt “something terrible” the night Alison went missing and drove to Rosewood. When she walked into Alison’s backyard she found the blonde buried underground and reaching for life. The former house mother pulled Alison out of the ground and drove her to the hospital. But when she returned to the car after seeking help, she discovered that Alison had disappeared. She claims that she hasn’t seen Alison since that night and that the blonde won’t turn up until she knows who she can trust.

9. A Ravenswood Party

The girls decide to head to a town party where they believe Alison will be. Mrs. Grunwald tells them that it’s too dangerous for them to “go chasing after her” but he Liars decide to ignore her advice. Instead they hop into a costume store and Hanna calls Caleb to help them crack into “A’s” computer by coming to Ravenswood.

10. “A’s” Identity Revealed

As the girls prepare for the party, “A” returns to his lair and is revealed to be none other than their English teacher, Ezra Fitz.

The Halloween “Pretty Little Liars” special will pick up where the season 4 summer finale left off -- with Emily, Hanna, Aria and Spencer dressed in their “finest Edwardian wear.” Attending the party in the Ravenswood cemetery, they’ll need to try to find Alison before “A” does. And as the girls try to figure out if Alison is really alive or not, Ezra will be lurking in the shadows.

Watch the season 4 “Pretty Little Liars” Halloween special, episode 13, “Grave New World” when it airs on ABC Family on Tuesday, Oct. 22 at 8 p.m.

Will you be tuning in? Let us know in the comments section.