Here is my 100% Achievement Guide for Guard Duty.
19 of the 20 Achievements are story related (Apart from the "Assassins Greed" Achievement)
This achievement is in the prologue.
Timestamps:-
Prologue - 3:05
Assassins Greed Achievement - 8:00
Act 1 - 14:30
Act 2 - 33:30
Act 3 - 1:01:40
Hope This Helps!