In his time as a party performer, Chester Johnson obtained numerous costumes including a clown costume, a woodpecker costume, a deer costume, a jester costume and a bunny head. When Chester was accidentally killed by Stan Hinkle and Phil Evans who believed that Chester had molested their kids, he was wearing his deer costume though the deer's head was left in his vehicle.
Chester's sister Rita Johnson, unable to bear keeping the costumes, eventually donated them all to various places including the local high school and a thrift store. However, her son Max kept Chester's deer head, likely as a memento of his uncle.
After Chester's death, he became a vengeful spirit. As his body was cremated, Chester's ghost became attached to his costumes, more specifically to their masks. A few months after Chester's death, 19-year-old college student Mike Hooks bought Chester's bunny head mask. When Mike tried on the mask to freak out his girlfriend Kylie Jennings, Chester possessed him and used Mike to kill Stan.
The murder came under the jurisdiction of Sheriff Donna Hanscum who suspected that there was something supernatural to it. As a result, she contacted hunters Sam and Dean Winchester who were unable to remove the bunny mask and came to suspect that it was a cursed object after learning of Mike's change in personality when he put it on and finding no signs of demonic possession. After the possessed Mike broke free and attacked, Officer Doug Stover was forced to kill him. The Winchesters and Donna burned the bunny mask and believed that they had stopped the murders due to their belief that the mask was cursed.
Shortly afterwards, Chester possessed a local high school student named Michelle when she tried on his jester costume and used her to seriously injure Phil before Michelle was restrained by Brock Buckner. After learning of cold spots from Brock, the Winchesters determined that they were dealing with a case of ghost possession and freed Michelle from Chester's control by shooting her with rock salt. Michelle identified Rita as the source of the costumes and after learning about Chester's "suicide", the Winchesters realized that he was the killer. The Winchesters got a list of the costumes from Rita and had Donna send Doug to collect them all.
While Doug was still collecting all of the costumes, an elderly gentleman named Steve Buress tried on Chester's old clown costume while playing with his grandson. This allowed Chester to possess Steve and use him to murder the comatose Phil. Before Chester could do more, Sam expelled the ghost from Steve using an iron railroad spike and recovered the clown mask.
Shortly after learning the truth about Chester's death, Sam was contacted by Donna who had successfully gathered all of Chester's costumes. Once Donna and Doug had the costumes, they burned them in the woods. However, Max still had Chester's deer head mask and became possessed once he put it on. Dean forced Chester's spirit from Max with the railroad spike and sent Sam to burn the deer mask, the last thing tying Chester to the Earth. Despite Chester's ghost manifesting to attack directly, Sam was able to burn the mask. With all of his costumes destroyed, Chester's ghost went up in flames.