The plan
It turned out that the murder had been planned a month in advance by Sheila and Rachel, during a physics class. The plan was to kill Skylar just before Rachel left for her Catholic summer camp. Rachel took a shovel from her father, while Shelia brought some kitchen knives.
Skylar thought they were going for a spin. They drove to the town of Brave, where they were going to smoke weed in the woods. The poor victim had no idea what awaited her. In addition to the kitchen knives, the future killers also brought metal pipes. This was premeditated.