Family Fortune Walkthrough – Hidden Treasure
By the Ruined Inn travel marker along the coastal road to the east of Fyresdal you’ll find a Hidden Treasure marker.
When you reach the location and have made the zone safe (there is a Monster nest almost directly on top of it that you should deal with first), enter the Inn and use Witcher Sense to find a glowing red chest. Loot this for a Letter – this will activate the side-quest ‘Family Fortune’.
Read the Letter in the Key Items section of the inventory. This will update the objectives.
Hop in the sailboat conveniently parked nearby and use it to quickly reach the next objective marker by a shipwreck in the bay to the southwest. As you arrive you’ll find that there are few Sirens patrolling the area. Hop into the water and have them attack you here so that you can crossbow them to death.
When the area is clear of baddies, enter the search zone, activate your Witcher Senses and find a chest (it appears as orange, not red). Loot this to complete the side-quest.