Once you start the chapter, you will need to enter Professor Elliott's mansion through a secret entrance at the back of his house. Sofia will enter the code and the doors will open to let you in. An elevator will take you to Elliott's room. Once you arrive, you'll find out that Elliott committed suicide with a Snub Pistol after learning that the shelter his sons and wife were in was under attack from the Locust. Troy will hack the codes from the Professor's computer to launch the Lightmass Missile. The Declassified Mission will be right in front of you.