The Fellowship of the Ring
Terror overcame Pippin and Merry, and they threw themselves flat on the ground. Sam shrank to Frodo's side. Frodo was hardly less terrified than his companions; he was quaking as if he was bitter cold, but his terror was swallowed up in a sudden temptation to put on the Ring. The desire to do this laid hold of him, and he could think of nothing else. He did not forget the Barrow, nor the message of Gandalf; but something seemed to be compelling him to disregard all warnings, and he longed to yield. Not with the hope of escape, or of doing anything, either good or bad: he simply felt that he must take the Ring and put it on his finger. (1.11.144)
Pippin felt curiously attracted by the well. […] Moved by a sudden impulse he groped for a loose stone, and let it drop. He felt his heart beat many times before there was any sound. Then far below, as if the stone had fallen into deep water in some cavernous place, there came a plunk, very distant, but magnified and repeated in the hollow shaft.
"What's that?" cried Gandalf. He was relieved when Pippin confessed what he had done, but he was angry, and Pippin could see his eye glinting. "Fool of a Took!" he growled. "This is a serious journey, not a Hobbit waling-party. Throw yourself in next time, and then you will be no further nuisance. Now be quiet!" (2.4.160-1)
"It is grim reading," [Gandalf] said. "I fear their end was cruel. Listen! We cannot get out. We cannot get out. They have taken the Bridge and second hall. Frár and Lóni and Náli fell there. Then there are four lines smeared so that I can only read went 5 days ago. The last lines run the pool is up to the wall at Westgate. The Watcher in the Water took Óin. We cannot get out. The end comes, and then, drums, drums in the deep. I wonder what that means. The last thing written is in a trailing scrawl of Elf letters: they are coming. There is nothing more." Gandalf paused and stood in silent thought.
A sudden dread and a horror of the chamber fell on the Company.