Markos suspects that newcomers in league with the Cyclops have arrived on the east coast of Kephalonia, and has suggested that you take them out and steal their loot to help pay for the Vineyard and ensure they do not cause any further trouble. Make your way to their location, as shown below.
As you approach their camp, use Ikaros to scout and determine the amount and location of the thugs. When you have killed them all, a cut scene will initiate during which you will meet Elpenor. When the cut scene ends the quest will complete, but before going to Ithaka to begin the next quest, 'Penelope’s Shroud', be sure to finish looting the camp.