Obtain this trophy by defeating 10 enemies in a row with headshots. You can do this easily with a silenced pistol at the end of chapter 3.
When you arrive at the large gate that leads directly into chapter 4, there will be a bunch of enemies patrolling the area. Enable the auto-aim function and equip the silenced pistol (which you can get either from the lockbox in the back of the truck by the waterfall, or by unlocking it post-game) – auto-aim will automatically target an enemy’s head.
Purposefully get detected by the enemy so that reinforcements will spawn, and there will be more than 10 targets in the area to play with.