Following the Qun

While back at the estate, read your mail and you'll be called in to see the Viscount. He'll instruct you to talk to the Arishok. Attempt to head to the docks and you'll be ambushed by a band of mercenaries in the Winding Alley. They aren't much trouble, so simply kill them and enter the Qunari Compound.

Speak to the Arishok and you'll find out that the Viscount and his son are meeting in the Chantry. Head there and you'll be attacked by Templars. They aren't any more trouble than previous encounter: simply kill the weaker enemies with area effect magic before taking on the stronger Templar leaders.