High Noon Trophy
Complete Chapter 17
Story related, cannot be missed.
Unlocks for completing Chapter 17: High Noon, where you'll have the choice to save either Ali or Hossein. Both of these choices will have an effect on your ending and they each have a trophy attached to them (see Baradar: My Brother and Doshman: My Enemy ), whichever choice you make will end the chapter and the trophy will unlock.