This is a Storyline quest.
Lasko: "Manny, there, he's a good lad. But a wrong he's done 'is captain chains his soul in grief."
Manny: '"There's a debt I owe, and I can't move on from this world until I pays it back. Before I joined Ratbeard's crew, I sailed with a pirated named Zadok. He set out to find a lost city of gold, an' we found the way to it. The passage to that city lies in this very cave, through that tunnel. Zadok found the Key that opens that ancient door. We were rich! We thought... But then we heard a terrible roar from the passage. Me an' me lads turned tail - we left the captain behind! Fearin' our doom, we shut the door! I'd pilfered Zadok's Key, y'see. I locked the door, sealin' me captain in forever. They've called this place Traitor's Cave ever since. Zadok's been stuck in that cave all this time. The guilt's too much! I beg you - go save him. You'll find the Key in that chest there."
Zadok: "Are you... real? Or another dream? Been trapped here so long, I lose track. Manny sent ye? That mutinous rat! I... wait, who's Manny again? Wait, listen to me! Look up there - see that hole in the ceiling. There's a lost city up there, a city of gold, just waiting t'be plundered! When me crew left me here, I had nobody to work the Winch, y'see. Couldn't go up, no. But now that ye're here, we can go... NO! The Key! The Winch, it needs a Jade Key - an' it's gone! The cursed Cave Lizards, they took it. Get it back from 'em in that cave, then we're rich!
(After recovering the Jade key)
Zadok: "Who's there? Get back! This place has mighty- oh wait. It's you again! You're back! You were gone so long... or were you? Did you find... the Key! Yes! Here - now we can... but do we dare? The city - it's not empty! There are things up there. Big things. The old book said the Ancient Ones were gone, but they're not. I've heard them roaring... thundering.. No, it wasn't a dream! Wasn't it?'"
Bonnie Anne: "The Ancient Ones aren't the only ones who've goe. He's gone... gone completely barmy, Captain!"
Zadok: "NO! No. I'm not crazy. I'm not. It just... may be very dangerous. Yes! That's it! Very dangerous! You go first. Besides - the Winch can only be turned from down here. You climb in the basket. I'll work the Winch. And then the gold will be ours! Won't it?"
(After going up the Winch)
Oxlahun Zotz: "But no. You are not that one. Whoever you are, I need your help!"