Antabolis Informant

Antabolis Informant is the second of the Morrowind Main Quests, after Report to Caius Colades. Caius Cosades will ask you to visit Hasphat Antabolis in the Fighters Guild, Balmora, to learn what he knows about the Sixth House.

Hasphat Antabolis
Hasphat will confirm that he does indeed have information for Caius, however, he wants something in return. He desires a Dwemer Puzzle Box, and he says that one can be found in Arkngthand. Travel there by following the instructions he gives you, and arrive at the ancient Dwemer ruins.

Arkngthand
The ruins are rather confusing, however, the Dwemer box is not very deep inside. After proceeding down to ground level from the entrance, head to the centre of the wide open room. Next, proceed up the small ramp directly in front of you. From there, you should be attacked by two bandits. (On the second level of the ruins). On this level, there is a small door nearby. Go through there, and kill the other bandits. Inside this room, there is the Dwemer Puzzle Box. Take it, and return to Hasphat.

Hasphat Antabolis
Speaking to Hasphat again will result in him giving you "Hasphat's Notes for Cosades". (Feel free to read this at your leisure before returning to Caius. There is no disadvantage to doing this. When you are ready, return to Caius Cosades for the completion of the quest, and your reward. Speak again to Hasphat after you have spoken to Caius, and he will inform you that the Puzzle Box is actually a Key, which he will give you.

Rewards

 * 1) Information about the Sixth House (House Dagoth)
 * 2) Increased rank in the Blades