[. . .]
At length they stirred and looked up, and began to search for anything that would give them tidings of Balin's fate, or show what had become of his folk. There was another smaller door on the other side of the chamber, under the shaft. By both the doors they could now see that many bones were lying, and among them were broken swords and axe-heads, and cloven shields and helms. Some of the swords were crooked: orc-scimitars with blackened blades.
[Bones in The Chamber of Mazarbul]
There were many recesses cut in the rock of the walls, and in them were large iron-bound chests of wood. All had been broken and plundered; but beside the shattered lid of one there lay the remains of a book. It had been slashed and stabbed and partly burned, and it was so stained with black and other dark marks like old blood that little of it could be read. Gandalf lifted it carefully, but the leaves crackled and broke as he laid it on the slab. He pored over it for some time without speaking. Frodo and Gimli standing at his side could see, as he gingerly turned the leaves, that they were written by many different hands, in runes, both of Moria and of Dale, and here and there in Elvish script.
[Recesses in The Chamber of Mazarbul]
[. . .]
'The Chamber of Records,' said Gimli. 'I guess that is where we now stand.'
[. . .]
'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. (We Cannot Get Out)
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.
[The Book of Mazarbul]
[. . .]
'Back to the hall,' answered Gandalf. 'But our visit to this room has not been in vain. I now know where we are. This must be, as Gimli says, the Chamber of Mazarbul; and the hall must be the twenty-first of the North-end. Therefore we should leave by the eastern arch of the hall, and bear right and south, and go downwards. The Twenty-first Hall should be on the Seventh Level, that is six above the level of the Gates. Come now! Back to the hall! '
[. . .]
'There are Orcs, very many of them,' he said. 'And some are large and evil: black Uruks of Mordor. For the moment they are hanging back, but there is something else there. A great cave-troll, I think, or more than one. There is no hope of escape that way.'
'And no hope at all, if they come at the other door as well,' said Boromir.
'There is no sound outside here yet,' said Aragorn, who was standing by the eastern door listening. 'The passage on this side plunges straight down a stair: it plainly does not lead back towards the hall.
But it is no good flying blindly this way with the pursuit just behind. We cannot block the door. Its key is gone and the lock is broken, and it opens inwards. We must do something to delay the enemy first. We will make them fear the Chamber of Mazarbul!' he said grimly feeling the edge of his sword, Andúril. (Balin's Camp)
[. . .]
The passage was lit by no shaft and was utterly dark. They groped their way down a long flight of steps, and then looked back; but they could see nothing, except high above them the faint glimmer of the wizard's staff. He seemed to be still standing on guard by the closed door. Frodo breathed heavily and leaned against Sam, who put his arms about him. They stood peering up the stairs into the darkness. Frodo thought he could hear the voice of Gandalf above, muttering words that ran down the sloping roof with a sighing echo. He could not catch what was said. The walls seemed to be trembling. Every now and again the drum-beats throbbed and rolled: doom, doom.
Suddenly at the top of the stair there was a stab of white light. Then there was a dull rumble and a heavy thud. The drum-beats broke out wildly: doom-boom, doom-boom,
and then stopped. Gandalf came flying down the steps and fell to the ground in the midst of the Company.
[The First Flight of Stairs]