This is story related and cannot be missed.
Details with minor spoilers.
*** Spoiler - click to reveal ***When you reach the monastery, talk to the patriarch. Your first two conversation choices are Kate & Hans. After you exhaust them, talk about the mission. This gives you the opportunity to ask about the mission a second time and to request help. The conversation leads to shroud. After you show Hans's shroud to the patriarch, the achievement unlocks.