After completing Tranquility, go to The Hanged Man tavern. There will be a cutscene where Lucky and his gang are demanding payment from Isabela. After they are beaten by her, you can talk to her. She will ask Hawke to provide backup for a duel she has set up with an old acquaintance, who she fears will not play fair.
After the ambush has been dealt with, Isabela instructs Hawke to check the bodies for information on the location of Hayder. When the note is found, his location is revealed to be in the Kirkwall Chantry.
After making your way through more of Hayder's men, you confront him inside the chantry. He insistently questions Isabela about the location of the relic. When she claims that she lost it, a confrontation ensues, culminating in Hayder's death.
Notable items EditSailors' Rope Belt
+3% physical damage
+3 fortitude, dropped by Hayder The Bodice Ripper
Requires: Dual Weapon
Damage: 17 physical damage
(31 per second)
+3% critical chance
+7% critical damage, dropped by Hayder
Isabela joins the party.
With Hayder's death, Isabela reveals that since Hayder cannot inform Castillon, their employer, about her lack of progress with the relic she will have to acquire it one way or another.