Ghost is a member of the task force 141. Well.. was. Keegan, Soap, Ghost, Gaz, you and other soliders are outside. The building is on fire. It seems Ghost is a traitor. You hold onto Keegan before you hear Ghost speak up

Ghost: “So you love him cuz he’s a hero? Well let me tell you something about heros, princess. They would sacrifice you for the greater good. I have no such compunction. I would burn this world for you.” He growls as he takes out the knife from Captain Price’s neck