1. Reaper's Coast - caravan remains
2. Reaper's Coast - The Wreckers Cave entrance
3. Driftwood - Undertavern entrance
4. Driftwood - magister Julian
Near the bridge to Driftwood you can find caravan remains  and Dwarf Warmaiden. If your Persuasion is high enough then you can manage to convince the Warmaiden to tell her version of events. After that she runs away.
Warning: If you have Spirit Vision ability then you should use it near the caravan. The ghosts will tell you the entire story that is necessary to complete this quest.
During your exploration of cliffs, you can find a group of dwarves that seem to be under influence of some sort of force. Most of them will attack you. Only one of them will want to speak with you. The person tells you that caravan remains were taken to The Wreckers Cave . If you have enough points in Persuasion then you can learn that this person works for Lohar.
If you want, you can go to the ruins next to the entrance to The Wreckers Cave and eliminate a group of "possessed" dwarves. However, if you don't want to do that, you can simply go back to Driftwood and inform one of the two people about the caravan's fate.
Choice 1: You informed Lohar
Lohar can be found in Undertavern . You can speak with him there and tell what happened with his caravan.
Choice 2: You informed magister Julian
Julian  is located on one of the piers. During the conversation, you must mention the lost caravan. When he asks you, what did you learn you can choose one of the available versions, you don't have to tell the truth.
Reward: 2000 experience points