11. Out of Mind, Out of Sight

Complete story — includes the ending

In the locker room, a student hears laughing but sees nothing before being beaten with a floating baseball bat. Later, Harmony is pushed down the stairs by an invisible force and injures her leg. Buffy deduces that Marcie, a missing student, is behind the incidents. Angel tells Giles that he can find an ancient book vital to Giles's research about The Master. Giles suggests that Marcie has become invisible as a result of being ignored by everyone at school. Cordelia asks Buffy for help and confesses that, despite being popular, she often feels alone. Marcie locks Xander, Willow, and Giles in the boiler room and opens a valve, filling the room with gas. Angel rescues them and gives Giles the book. Marcie kidnaps Cordelia and Buffy and ties them up at the Bronze. Marcie plans to disfigure Cordelia's face, slashing it once before Buffy breaks loose. Initially hampered by being unable to see Marcie, Buffy uses her Slayer senses to focus and defeat her. FBI agents arrive and take Marcie to a school with other invisible students to learn about assassination.