Randy has a surprise for the family, he gives them gifts and takes them out for a ride to a new business venture he's bought for $10,000. An old closed Blockbuster location. He takes them out to see their new business. He and the family man the store and on their opening weekend they get exactly zero customers. In fact anyone those comes near the location is afraid to go inside. While walking through the store Randy spots a patron and he offers to help, only to have the patron (a woman dressed in 80s attire) disappear like a ghost that she is. While another ghost is floating around, Randy continues to defend his position that his idea to buy this place was a good one. Stan spots his dad arguing with himself and suggest to his mother that something might be wrong with dad; she of course is already very much aware of it. On Halloween night, Cartman and Kenny are going over to Kyle's when they run into Butters and Jimmy who are already in the costumes (a Were-Leprechaun and the Gangnam style guy, respectively). Cartman says their costumes are so awesome they've got to puts theirs on together. At the video store Stan has put on his Captain America costume, but Randy doesn't want him to go trick-or-treating in anticipation that tonight is going to be a big night for the video store. Randy is convinced they are going to busy. Stan calls Kyle (Thor), Kenny (Iron Man) and Cartman (Hulk) with the bad news. Kyle comes up with an idea that will allow Stan to participate. They use FaceTime on their iPads that allows Stan to accompany them with Kyle's iPad mounted to a skateboard. At the first house they arrive at, everyone's costume is readily identified (even Stan's), except for Cartman's when he is confused for Bruce Vilanch, Chas Bono or Harvey Firestein and a green Honey Boo Boo. A couple is walking by "that old creepy place" (the Blockbuster) when she thinks she spots someone in the window (Randy) and they quickly hurry on their way.
Randy is walking around the video store slowly becoming possessed by something, when a man appears behind the counter suggesting that perhaps Randy should consider eliminating the negative influences in his business, his son and wife. For the moment, Randy is very much against the idea of doing anything to his little boy. Meanwhile, the Avengers are trick-or-treating when they spot something going down at the Kum & Go. A man has broken into the convenience store to break into the Redbox video rental machine. Inside the boys encounter that man, plus three accomplices, who've murdered the clerk and got very little money from the Red Box. The Avengers quickly go to make their escape, chased by the thugs. But the thugs did manage to grab one of the Avengers, Captain America. They try grilling Stan to find out where the other boys have gone to. The thugs find a flyer for the costume contest at the community center and realize that is where the boys are going. As they no longer need Captain America, they throw his "body" off of a cliff. At the video store Randy has begun a transformation into the Jack Nicholson (Jack Torrance) character from "The Shining." At the bottom of the cliff that Captain America was thrown down, a couple returning from a Halloween party finds Stan's face on the iPad. He asks for their help in getting him to his friends.
At the South Park Police Station Kyle, Kenny and Cartman are telling the police about what happened at the Kum & Go. The cops know them as the Red Box Killers. iPad Stan is over at the hospital giving his statement to a policeman. The other boys and the cops go over to the hospital where Stan tells them about the killer's plans to go over to the community center to find the other boys. The cops won't cancel the Monster Mash event, after all it is a graveyard smash. The cops decide they are going to have to send one of the Avengers into the Monster Mash in disguise. Kyle's iPad, with Stan's image becomes the face and head for a police officer who is dressed Gangnam-stein. At the video store, Randy is stalking the aisles looking for Stan, meanwhile Shelley is setting the place on fire. Stan is about to identify the Red Box Killers to everyone at the Monster Mash when his dad takes over the iPad. The cop that Stan was directing now has no idea what to do and starts terrorizing everyone, even a family in a nearby house watching streaming video on their X-Box and iPads. The cops shoot the monster (their fellow officer), and also manage to catch the Red Box Killers. There may still be time for the costume contest, except that Stan's battery is dying. The Blockbuster is on fire and outside of it Randy has become frozen a la Jack Torrance. Sharon tells him that insurance company is going to let them get most of their money back. Stan replaces the DVDs in his dad's hand with an iPad.