The Final Voyage

 is a quest in.

Walkthrough

 * In order to complete the quest, you need to find Lofell's missing crew members. This is done by completing the first part of the quest A Paradise of the Mind, a summary of which is below.
 * After talking to Lofell, leave Neketaka and head for Splintered Reef at the southeastern corner of the map. The area is a wasteland of shipwrecks inhabited by undead. The residents are under the effects of a spell which makes them believe that they're regular kith. Head to The Pickled Eel and talk to Copperhead to find out more. After the conversation, Zulka and her crew enter the inn with a pair of captives, who are promptly carted to the back room.
 * In order to get to the captives, you'll need to kill Zulka and her crew (along with the rest of the inn's inhabitants, who are commanded to attack as soon as you're spotted by Zulka). Alternatively, if you complete the quest A Paradise of the Mind by making a deal with Menzzago, Zulka and her crew will no longer be present, allowing you to approach the captives freely.
 * Talk to the two captives in the back room. You can examine the iron collar on them using Arcana 15 to determine that the collars possess a similar incantation to the marks on the foreheads of the undead. Doing this, or talking to Copperhead in the boatshed allows you to tell them what is going on. The female captives mentions that they were sailing under Lofell and his ship, the Antelope. After being attacked by The Floating Hangman, they (herself, Kesango, and Daimo) were taken captive by the crew of undead and were brought back to the reef.
 * Tell them to flee (either through the hole in the ship, or through the front door if it's been cleared - it doesn't matter). They will supposedly return to Fort Deadlight, netting you moderate positive reputation with the Príncipi.