 Retiring Head of the Presidential Detail Special Agent-in-Charge Martin Walker (James Woods) brings Sawyer to the PEOC beneath the Library.Inside, Walker kills Sawyer's detail, revealing himself as the leader of the attack, apparently seeking vengeance against Sawyer for his Marine son, who was killed in a botched mission in Iran the year prior.Cale kills a mercenary, taking his weapon and radio, and rescues Sawyer after overhearing Walker.