After coming to live with local sheriff Jody Mills, Annie "Alex" Jones started going to school at Marshall. Due to her past, Alex had trouble adjusting and was noted by Jody to be smoking reefer under the school bleachers at times when Jody wasn't around.
Around a year later, Alex had turned her life around with the help of Marshall's math teacher Stephen Phelps who saw Alex's potential. She had also started dating Henry, the star of Marshall's football team and the most popular kid in school.
However, Marshall's new janitor was in reality Richard Beesome, a vampire that was seeking to destroy Alex in revenge for her role in his becoming a vampire and the deaths of his wife and son. Henry had in fact been turned into a vampire by Richard and aided him in his revenge plot by pretending to like Alex and helping to build her life up. The two vampires used the school's abandoned pool building, which had been shut down due to asbestos, as their nest.
Eventually, after a few months of building up Alex's life, the two vampires made their move by killing Stephen Phelps. Henry, who committed the murder, went so far as to string the man's body from the flagpole so that everyone saw it when they arrived at school the next morning. School was cancelled as a result of the murder for at least a day.
At the time of Stephen's murder, hunters Sam and Dean Winchester were in town, having been called in by Claire Novak who was insistent that there was a monster in Sioux Falls but whom no one believed. The strange circumstances of Stephen's murder proved Claire to be right and the investigation by the Winchesters and Sheriff Jody Mills, also a hunter, led them to grow suspicious of Richard due to his lack of reaction to Stephen's murder. Further digging revealed that Richard had gotten his custodian job at the school under the social security number of someone who was long dead.
After Jody, Claire and Alex were kidnapped, Sam investigated Richard's office and found an old plan of the school showing the old pool building. As asbestos had been found around the flagpole, the Winchesters were able to identify the old pool building as the vampire nest. Raiding the nest, the Winchesters rescued Jody, Claire and Alex and killed the two vampires.
The next day, Alex expressed her intention to return to school and a normal life. She eventually graduated from Marshall as Alex is stated to be going to nursing school a little over a year later.
- The school's old pool building appears to have been long abandoned after being shut down for asbestos. The building is clearly in a state of disrepair and features graffiti on the walls.