You can now either leave the ship quickly to avoid further confrontation, or stick around to fight off more pirates and collect some of the goods aboard the pirate ship. When Gaston is dead, search his body for loot (grab his key!). The tight quarters of the ship's cabin will make it hard to maneuver, but you can make the fight really easy by keeping a table between you and the enemy and attacking with a claymore. Gaston isn't expecting you so you should have a relatively easy time killing him. Enter the captain's cabin and you'll find the target, Gaston Tussaud. There you'll find a pirate ship you can board. Travel to the Waterfront District of the Imperial City. Talk to Vicente Valtieri and he'll tell you of a pirate that needs to be killed. Go inside and speak with Ocheeva to complete the quest. At the end of that tunnel is a doorway that lets you into the Dark Brotherhood headquarters. In the basement is a broken wall that opens to a tunnel. Once there, break into the abandoned house and follow the downstairs door to the basement. You're now instructed to travel to Cheydinhal. As you wake, Lucien will greet you once again. Once you've killed Rufio, sleep in his bed. He's very weak and should die without any trouble. Go into the lower level of the building (by way of the floor hatch) and enter the room at the far end of the hall. Travel to the In of Ill Omen, north of the city of Bravil. He'll give you a blade and your first quest you're to kill a man named Rufio. When you wake up, you should be met by Lucien Lachance. In order to initiate this quest, you must first kill an innocent person.