Nikki says her three-year marriage has turned volatile. She claims her husband, Mark, has punched her in the face, broken her nose and run over her toe with his truck -- among other allegations -- which he denies. Mark admits he has hit Nikki but says it happened only once. He claims Nikki instigates most of their fights and has violent outbursts, and he suspects she might be trying to kill him. The couple admits their confrontations happen in front of their two young children, and both say they want to save their marriage. Dr. Phil intervenes for the sake of their kids. Can this toxic relationship be healed?