After the death of Kodlak Whitemane, Vilkas is out for revenge. He will act as your follower as you make your way to the Silver Hand hide-out at Driftshade Refuge, a small fort southeast of Dawnstar. Upon arrival, kill the three Silver Hand members guarding the entrance and head inside.
Unsurprisingly, Driftshade Refuge is teaming with hostile Silver Hand members. If they prove too formidable, try working through them one by one with your follower going in first. In the two-leveled room with many boxes on the floor, make sure to search for the book An Explorer’s Guide to Skyrim which will add a few map markers for later exploration. It is located on a bookshelf beneath an elk head that’s mounted on the wall. You will eventually come to the second area of this dungeon, Driftshade Cellar.
After the first turn, make sure to loot the hidden treasure chest, then follow the path and make use of the Spike Wall trap to dispose of another enemy. Ignoring the locked cell containing the dead werewolf, activate the trap again and run into the area directly behind it for another treasure chest. Hit the pullbar on the wall to get back out, and head forward to the next room. Don’t leave this chamber without the Light Armor skill book The Rear Guard. Past this point the interior of this place resembles a snowy cave, and the next room is in two levels, with a Silver Hand sniper on the upper ledge.
After moving on and through a torture chamber, you reach another large chamber containing more enemies and more loot. Take the only available path to an initially inaccessible part of Driftshade Refuge. The first chamber contains the three remaining members of the Silver Hand, the One-Handed skill book 2920, Morning Star, v1, the Block skill book Warrior, a treasure chest with considerable loot and finally, the stolen Fragments of Wuuthrad.
After you’ve got everything, take the door to the south for an easy escape route back to the outside world, then return to Jorrvaskr in Whiterun. As soon as you arrive, Vilkas will inform you that you should meet up with your bothers and sisters at the Skyforge and pay your respects to the deceased, but now avenged, Kodlak Whitemane. This will end the current quest and start the next one, Glory of the Dead.