The Price of Honor - Skellige
Quest Giver: Timmon
Other Requirements: Have Keira's Magic Lamp
You'll find The Price of Honor quest in the village of Harviken by speaking with Timmon, a man standing outside a building near the docks. For this quest you'll need to travel to the eastern portion of the island, past the town of Trottheim. Here you'll need to find a corpse along the beach, examine it to update the quest.
If you have Keira's Magic Lamp then you'll have to use it near the corpse to update your quest - otherwise the quest will dead end here and tell you to return once you have a way to examine the area. After using Keira's Lamp and speaking with the ghosts here use your Witcher Senses and follow the foot steps to the east.
At the end of the footsteps trail you'll come across the brothers' corpses. Search the corpses for a key and a letter explaining more of what happened here. There is an optional part of this quest that you can do next which involves diving in the water nearby where you found the first body and using the key on a chest.
You'll find a Gold Diamond Necklace which sells for 600 Crowns at a vendor, a small reward for completing the quest but a reward none the less. A map location of where you can find this chest is shown below, my location is right on top of the chest. Either way, to complete the quest return to Timmon in Harviken and talk to him.