Between Darkness And Dawn (27th Mellon Chronicles)

The Witch King is very curious about the beings that have twice evaded and thwarted him. He wants to know who they are... especially the human. When he is poisoned, Aragorn's only hope of survival is to follow the Wraith's summons to Angmar, where the antidote lies. To stay with him now, Legolas must choose to walk willingly into the arms of the darkness that has once held him.