On a moonless night, Pearl Tevi walked into the sea, then returned to her fishing village bearing a cup formed of pure water.
Next morning, the corpse of a drowned fisherman lurched out of the surf and mouthed a warning that Pearl must hand over the magical cup to the Kelpies, or the sea beings would attack her village. But the Witch Woman divined that Pearl was a Bearer, and must take the cup upriver to the Walkers in All Worlds, the high priestesses in the city of Artoclan. The cup, she said, was one of the six Signs needed to drive back the Deathless who threatened the peaceful world of Northwok. When the Witch Woman was killed in the Kelpies’ attack, Pearl fled her village and took a keelboat to Artoclan, only to find that the Walkers had already chosen six Bearers. Pearl wondered how that could be, when she knows she carries the true cup. But when the chosen Bearers are all brutally murdered by Deathless spies in broad daylight, Pearl decides she must find the true Bearers and take them to the Walkers. The Bearers must carry their treasures over the Spine of the World into the Dark Lands and drive the Deathless back before they sweep over Northwok, the last bastion of freedom in a dark world.
Add to the list of phrases I never want to see again: the last bastion of freedom in a dark world (unless you are describing the cigar bar at Nat Sherman's).
You've got a run down of the plot and way too much going on here. Focus. Prune down to the essentials then tell us why it matters in non-cliche terms.