Of the Darkening of Valinor
Hearing that Melkor had fled and suspecting that he had gone to his strongholds in the north of Middle-earth, Oromë and Tulkas pursued him, but he had turned back and gone—unknown to the Valar—into the south of Aman, to the land of Avathar. There lived Ungoliant the spider, in endless hunger, and she devoured all light that she could find and spun forth webs of darkness between a cleft in the mountains. Melkor persuaded her into his service by offering her anything she demanded, a promise he did not intend to keep.
Amid a cloak of darkness, Melkor and Ungoliant surveyed the realm of Valinor, which was in a time of festival honoring the gathering of fruits. Manwë had planned the festival, intending to heal the feud between the princes of the Noldor. Fëanor was commanded to come, but Finwë and Fëanor's sons remained in Formenos, along with the Silmarils. Before the throne of Manwë, Fëanor met Fingolfin, who pardoned the threat Fëanor had made in Tirion and promised to follow him.
At the same time, the Trees mingled, and Ungoliant and Melkor came forth to Ezellohar, where the Trees stood. Melkor wounded each Tree with his spear and their sap poured forth, and Ungoliant drank them until they were dried and withered, swelling to a size that even Melkor feared and putting out clouds of darkness.
Darkness fell then on Valinor. The darkness—being made from the destruction of light—was malicious and all sight, sound, and will were lost. Manwë knew that it was the work of Melkor and Oromë and Tulkas set forth in pursuit of him, but they were lost amid the blindness and confusion of the darkness put forth by Ungoliant.