Shortly before the hunt for Zakhaev begins (Modern Warfare 1)

Price recruits you, a former MI6 agent who quit after a failed mission. He sees in you the potential and determination he needs for his special unit. One quiet night on an aircraft carrier, he tells you that he needs you "because ghosts like us won't rest until we've killed the damned monsters that hunt us."

As Price is about to bring you into Task Force 141, the ship is suddenly attacked by enemy fighters. You fight alongside him, and that's the moment you realize you might not be done with this life after all.