I found an abandoned campfire at the entrance to Broken Helm Hollow. I should figure out what happened to the campers.
Read the Notes
I found a sheaf of notes near the campfire. Perhas they will provide clues.
Talk to Seryna
I recovered the diamond. From the note, I should take it to Seryna, a fence in Riften.
Search the Cairn
Seryna took my diamond and directed me to the graveyard behind the Fighters Guild in Riften. Fresh flowers on the cairn indicate my payment is inside.
— game journal
Note: Players find three skeletons in the area, who obviously got in a fight with a Troll. Exploring the cave unlocks the Achievement Explore Broken Helm Hollow.