Darragh can be first encountered at the Last Light Inn, where he guards the entrance to the sanctuary and main plaza from behind the main barricade, below Terradissia and a few steps away from Elifer.
When Marcus attacks the inn and attempts to kidnap Isobel during Resolve the Abduction, Darragh more often than not fails the saving throw and be Impaled for the remainder of the battle. If Isobel is not saved, he and everyone in Last Light Inn turn into a Shadow-Cursed Undead, save for Jaheira.
If Isobel is saved at the Last Light Inn, and once the Nightsong has been freed from her cage and heads for Moonrise, Darragh follows Jaheira to Moonrise Towers. However, Darragh is killed during the fight against Absolute forces before the party members can arrive. His corpse can be found within Moonrise Towers itself, down the staircase leading down from the entrance, in front of Disciple Z'rell.