The Witcher 3: Blood and Wine - Father Knows Worst
This level 37 quest can be found in various locations including notice boards in Beauclair.
This quest provides an opportunity to complete an objective of the There Can Be Only One secondary quest, if you don't have this quest yet, grab it and progress to the appropriate point before proceeding.
Kick things off by approaching a cave northwest of Beauclair Palace. Enter to chat with the guest givers. You can ask them all about it before agreeing to head in and look for Hugo.
The cave is full of kikimora. After defeating them, look for a sword and a blood trail on the far side. When you come to a pool of warm water, take the path away from the search zone to optionally fight some more kikimora, collect some loot and draw from a place of power.
Back at the hot pool, cast Quen and dive in to loot several container sand collect a silk filter – user Witcher Senses to spot it. You’ll need to surface and recast Quen at least once in order to collect everything down there.
Continue along the blood trail to find Hugo. You can give the filter back to Hugo for an extra reward if you like. Whether or not you do so, you’ll have return to the mouth of the cave with Hugo. You can agree to attack Hugo’s brothers or say nobody needs to die to encourage the brothers to talk it out. You’ll be rewarded by the two brothers if you achieve a peaceful resolution, and unlock the Wisdom part of the There Can Be Only One quest if you’re on that.