The episode starts out with Mona in the Radley Sanitarium singing the song "Teddy Bear's Picnic" while painting a mannequin head. After she finishes singing she starts to explain why she was painting the mannequin head, for a Halloween art project. She then explains how staff at Radley don't like to bring up the holiday Halloween because it had bad connotations for some of the patients. Then the camera pans to a figure in a black sweatshirt in the back of the room. Mona says that Halloween is even better than Christmas - "more makeup". Then she stands up and walks over to the hooded figure and says, "And this is going to be the best Halloween ever." Then she hands the hooded figure three pills and four bullets and says, "I bet somebody's life on that."
In this special Halloween episode, Aria, Emily, Hanna and Spencer are looking forward to some good Halloween fun now that the traumatic events with Nate are behind them. But once aboard the Rosewood Ghost Train, the girls are in for much more than just some childish tricks or treats. With "A" running amuck and unexpected party-goers popping up at every turn, this Halloween event becomes one killer party. Plus, musical guest star Adam Lambert performs his songs "Trespassing" and "Cuckoo" during the Halloween festivities. #PLL #PrettyLittleLiars #PLLHalloween