When you reach the entrance to the bay, you will encounter three Athenian ships. Since they are blocking any entrance, you must destroy them. Focus your attacks on the smaller ships before you take on the large one in order to minimise incoming damage. You can then completely destroy the large ship, or you can board it when the health of the ship is low so that you can loot any valuables. Once they are dealt with, you can sail into the bay.
Warning! You will note that destroying the Athenian ships has prompted a bounty to be placed upon you. Remain vigilant of any bounty hunters by tracking them from the Mercenaries menu. If you want to avoid the bounty hunters altogether, you can pay off the sponsors via the map, kill the sponsors in the world, or keep a low profile until the bounty expires.
When you enter the bay a cut scene will follow, after which you will be speaking with Stentor. At this point it does not matter which dialogue you choose as Stentor will not believe that you are his brother. Instead you must proove yourself in battle before you can meet with The Wolf. After speaking with Stentor the quest will complete.