Until the End by Christopher Pike

Combined into one novel is the Final Friends trilogy where sophomore Alice McCoy decides to throw a party that no one will ever forget at the beginning of the school year. She definitely gets what she wanted when, at the end of the party, someone is ***ed. Although written off as a suicide, Michael Olsen believes that nothing adds up; it leaves him disturbed and intent on figuring out the truth behind his friend's death. Nowhere is safe for the students of Tabb High School—not the homecoming dance and not even graduation.