During their fight, Steve inadvertently removes a latex mask from Amos's face, revealing him to actually be Principal Kastleman in disguise. Kastleman explains how years ago, Kathy discovered she was pregnant with Steve's child, after which Kastleman murdered her in a rage and hid her body in the school basement before killing multiple students. Callie and Steve manage to overpower Kastleman, impaling him with a javelin.
As they clashed, Steve accidentally removes a latex mask from Amos's face, revealing that he is actually Principal Kastleman in disguise. Kastleman explains that years ago, Kathy became pregnant with Steve's child, and in a fit of rage, he murdered her and hid her body in the school basement before killing several students. Callie and Steve ultimately overpower Kastleman, piercing him with a javelin.