Kevin, a man with 23 distinct personalities, has been under the care of his trusted psychiatrist, Dr. Fletcher. However, a dangerous 24th personality lies dormant, ready to emerge and overpower the others. When Kevin abducts three teenage girls, led by the resourceful and observant Casey, they find themselves trapped in a terrifying fight for survival. As the boundaries between Kevin's personalities begin to collapse, a brutal battle unfolds within him, with everyone caught in the crossfire.