When running around for quest and exploring The Chasm, you might some Fatui Action Log. There’s 4 logs scattered across The Chasm Underground and reading all 4 will get you secret achievement: If Not Us, Then Who?.
Without further ado, here’s all location of Fatui Action Logs in The Chasm:
Fatui Action Log I
Head to nearby teleport waypoint then walk south until find some tent. You will find first note on top of wooden box.
Fatui Action Log II
Start from teleport waypoint with red circle then walk southwest.
Fatui Action Log III
Fatui Action Log IV
Located east of The Glowing Narrows teleport waypoint.