Talk to Copeland to start this mission. Drive to the marked location to find a search area. Examine the corpse leaning on a concrete roadblock to find the trail. Follow the tracks until you reach the next search area.
Find the corpse by the stream near the wooden bridge and examine it to find the next set of tracks. Follow them to reach another search area.
In this search area, find another corpse beside a large boulder. Follow the tracks again which will now lead you to the Camp.
There’s only a handful of enemies so I suggest walking to the top of the hill where you can find a lookout that you can take out stealthily. From there, you can take out the hostage takers then approach Copeland’s man to free him. Mission complete.