At that moment a shadow fell over them. The bright moonlight seemed to be suddenly cut off. Several of the Riders cried out, and crouched, holding their arms above their heads, as if to ward off a blow from above: a blind fear and a deadly cold fell on them. Cowering they looked up. A vast winged shape passed over the moon like a black cloud. It wheeled and went north, flying at a speed greater than any wind of Middle-earth. The stars fainted before it. It was gone.
They stood up, rigid as stones. Gandalf was gazing up, his arms out and downwards, stiff, his hands clenched.
"Nazgûl!" he cried. "The messenger of Mordor. The storm is coming. The Nazgûl have crossed the River! Ride, ride! Wait not for the dawn! Let not the swift wait for the slow! Ride!"