The X-Files: Bad Sign is a novella written by Easton Royce. It was first published in 1997.
Description[]
When agents Mulder and Scully are called in to investigate the bizarre, ritualistic murders at Grover Cleveland High School, they stumble upon a strange planetary phenomenon-- one that might have a disastrous effect on two cheerleaders.
But are Terri and Margi really being controlled by the cosmos, or are they just out for revenge?