Find and rescue Revyl Kylar at ( -490, 0, -183 ) /waypoint -490, 0, -183
You need to kill six lvl 20▼▼▼ gnolls to free him. This will probably be difficult even at 20, however, the revive point is fairly close so you can kill a few, run back, then kill the rest.
Escort Revyl Kylar back to his father.
Lord Kylar will recognize that his son is safe when his son is physically in front of him. You may have to move around a bit to get Revyl close enough to his father. Once he gets close enough he should approach and face his father. Just running to the keep alone won't update the quest.