This is a fairly short mission. All you really need to do is to follow your friends through the entire area. After going through the clean room and your friend talks to the soldiers, look on the couch to the left just before the next door for Diary Note [Note 1/1] . Continue through the next few doors and proceed along the crowded room to the conference hall at the end for a scene.
During the scene you will be in a lengthy corridor. Simply walk up and open doors to see various scenes. Once you have opened enough doors and seen enough scenes, you will return to Polis.
After another brief story sequence, the mission will be over.
Note: At this point, you will earn the Achievement/Trophy ‘Revelation’.