Limthir saw something on the banks of Anduin, but speaks of it only in hushed tones: it was one of the Nine, one of the Nazgûl.
'It was dark as pitch, in the cold watches of the night, and I walked the shore of Anduin. I thought I saw... no, I did see... a darker patch of shadow in the space between the trees. When I approached, it fled. It moved with a lurching step, sliding low upon the ground, but it moved quickly, and for some reason I cannot explain I was loath to close the distance. I lost it in the dark.
'But I know the name of this apparition.'
Limthir looks from side to side, and then speaks in a voice barely above a whisper.
'Its name is Nazgûl. Bring word to Fimloth at Haldirith that one of these fell creatures is loose somewhere in Thinglad.'
Fimloth is at Haldirith, in Thinglad.
Limthir saw the shape of what he believes to be a Nazgûl on the shores of Anduin, and wants you to warn Fimloth that such a creature is loose in Thinglad.