This quest begins as soon as you ask the Sea Scholar about Adamar.
Ask about Adamar
Yes, what can I do for you? Oh... you say you are looking for someone named Adamar? Hm... Adamar... Adamar... the name sounds familiar.
Oh yes! I remember a man that went by that name. He came by here recently in search of some information regarding a cursed chest. While we do have information in regards to such an item, we can't just give it out for free. I told Adamar that if he wanted the information, he needed to retrieve an item for us. Unfortunately, he hasn't returned. Perhaps you'd like to pick up where he left off?
Ah, the brew! Thank you. You have done well. I hope the journey didn't cause you too much trouble. Now, I suppose you'll be wanting information regarding that chest? Very well.
A few years back another came in search of such a chest. A strange man who seemed dead set on finding it at all costs. He went only by the alias, The Innkeeper. At the time the cursed chest was in our possession and he offered us a substantial amount of gold in exchange for the item. Seeing as we didn't have the knowledge to open it, it seemed rather useless to keep it so we gave it to him in exchange for the gold.
I imagine this Innkeeper would still have such an item. Speak to him, and good luck on your journey.