When you enter Dead Men's Respite you are welcomed by a ghost bard that presumably wrote Olaf's verse. When you follow the bard through the dungeon, he will lead you up to a sealed door and will go to the right of that door, and eventually you will find the book. Now, walk back to the sealed door.
The bard will greet you again and will break the magical seal on the door.
You will see a short scene where the bard will challenge King Olaf; a fight will commence.
After this, there will be a backdoor leading out which you will need to open through a chain on the wall, leading back to the entrance tomb of the dungeon.