Part one can be found here.

When the enemy army was approaching, panic befell the castle and all of its people.

The princess was escorted by her knight up to the tower in the southern wing of the castle. How he had not heard that they were to leave the castle, nobody knows, but he did not make his way outside. Many tellings of the tale say that the invading forces gave them no choice but to flee up to the tower; a few suggested that he meant her ill will. Whatever the truth was, they never left the tower again.
In all the chaos, the tower was blocked off, and the last few to leave insisted that it was empty. Its doors were barricaded, and nobody went near it. Even when the search was on to find the princess, nobody had any idea that she might be in the tower.
The truth– which nobody else but the princess and her knight know– was that he had put her into a room at the top, and closed the door. He then engaged in battle with several invading warriors. Bravely though he fought, there were many if them, and in the end he perished. His body, heavy with all of its armor, was left laying against the old wooden door to the room which he had been guarding. The invaders, not knowing about the process inside– for she had hidden herself well and quietly– left the tower, and were glad that they had defeated an enemy knight so strong.
When the princess heard the men leaving she crept out of her hiding place. It was quiet in the Hall, and called out to her knight. The longer she called his name, only to hear no response from him, the more her panic grew.  She began to pound on the door.  When she tried to open it, it would not budge; she realized that she was trapped inside.  Her calls became screams, but they were never answered.

Years passed, and the princess was all but forgotten.  A new ruler took the castle, and set about restoring it so that it might live in glory once again. As the masons, architects, and other workers finished up other parts of the castle, patching up whatever needed the most work in order for it to be livable, curiosity grew about the southern tower.  Servants were sent there now and again to get the place cleaned up, and masons went to inspect the various floors and rooms to see what needed changing and updating. The higher they got in there in the tower as they worked, the more often they heard strange noises.

The king had no interest in hearing about what anyone had heard.  He was certain that they had been nothing but evidence that the tower was in need of repair; a broken window, a creaking stair, perhaps a missing brick that let small animals through.  All he cared about was having the tower cleaned and repaired, so that people could live in it once again.  He sent in soldiers to help with the removal of the suits of armor that laid about, and gave ordered that nobody was to bother him about the noises in the tower.

After that, each time a suit armor, various remains rattling around inside inside of it, was carried away, they could hear a distant pounding.  When the dust that had caked the floor over the centuries was disturbed by a broom, faint voices, as though from far away, drifted through the halls.  Most of the time, the maids and masons and soldiers shook their heads and assumed that it was nothing more than their imaginations.  They remembered the king’s words, that the noise was probably from one of the rooms that needed repair, and as such was nothing to worry about or put much thought into it.

Another floor higher, and the voice grew louder, the pounding more insistent. Another suit of armor gone, and more noise. Another floor cleared, and there it was again. Time went on, and the workers in the tower started to swear that they could hear a young lady’s voice, a soft voice, but a desperate one.  It seemed as though some door was rattling with the pounding that they could hear, but still they could not place where it was coming from.

They assumed that it was someone among the crew playing a cruel trick.  Nobody had been in that tower for ages aside from that crew; it was impossible for it to be anything else.  Besides that, every now and then, one of them– sometimes a maid, sometimes a soldier, other– would abandon their work.  They could be found nowhere, and the others assumed that whoever was missing had been causing the ruckus just to scare them.

Eventually, the work was delayed enough, and morale so disrupted, that the captains decided that the crews working in the tower should all be put to different tasks, and a new crew brought in. These new soldiers and servants found out all too soon about the strange noises echoing through the tower. There were still plenty of suits of armor to removes, and floor that needed dusting, and the pounding and calling voice only became more frequent, more insistent.

They got to the top floor at last, but not without rumors of what was going on spreading here and there. Theories that it was one of the old crew members sneaking in to cause a ruckus, and then stories of ghosts. They knew from the amount of armor that they were removing but there had once been a battle here. They had heard about the time that the castle of been attacked, and recognized the armor of the once-enemy kingdom. In the spirit of the peace that the realms had enjoyed for generations now, They thought it best to melt down the armor and forget it into something new.

What they did not expect to find was the suit of armor bearing the crest of the ancient royal family, along with the insignia for the highest-ranking order of knights. The weak points in the armor has been pierced by various weapons, and although there was no flesh left to speak of underneath all of the metal, the workers and the soldiers knew that whichever night this had been, he have been very important to the royal family.

Strangest of all, as soon as anyone touched the armor, a horrible banging began on the door on which the armor leaned. When the crew backed away, the noise stopped. When they stepped close again, and shifted the suit, there was the banging again, the door rattling as though beaten by a pair of terrified fists. This time, when the armor shifted, it fell over on its side, and they heard screaming. A voice was calling out, desperate to be heard.

“Let me out!” they heard the voice cry.

One of the maids nearly fainted.  The soldiers did their best to feign bravery.  That had been a young lady’s voice.  Yet… how could anyone possibly be in that room?

“What is going on here?” one of the soldiers demanded to know.

The terrible pounding on the doors resumed.  “Please!” the young lady’s voice called again, this time more desperate than ever.  “Sir Gavin, you cannot leave me here!”

The crew looked to one another; none of them went by the name Gavin.  They glanced down at the suit of armor, which now held nothing but bones.  The door rattled with the pounding.

“Make it stop!” one of the maids cried, covering her ears.  “Just open the door!”

The soldiers looked to one another.  The suit of armor was not particularly heavy; they could work together to move it and find out what was on the other side of the door…

“One shoulder each, then,” one suggested.

The other nodded, though he seemed nervous about disturbing the body.

Together, they dragged the suit of armor, skeleton and all, over to an adjacent wall.  A sword clattered to the floor.

“Sir Gavin!” the voice called out again.  “Do not abandon me now.  You have been my only comfort all this time…”

“Just a moment,” one of the soldiers replied.

He stepped over to the door, and turned the handle.  As it creaked, the voice grew fainter, and the pounding subsided.  It took him a few twists back and forth to get the knob to really turn, but eventually it gave way with an echoing click.  He pulled opened the door, and gasped at the sight before him.

There, in the middle of the opposite wall, stood a four-poster bed.  Unlike everything else in the tower, it was clean, free from the layers of dust that coated everything else.  on the bed there was a solitary figure, laid out like a sleeping girl from an age-old fairy tale.  The soldier approached, his breaths ragged.  Even the flowing of his blood seemed loud, now that the creaming and the pounding had stopped.

The figure wore a silken gown of a bright and festive color, as well as a jeweled necklace.  on her head rested a thin silver circlet, a treasure lost by the royal family long ago.  The soldier could say nothing; he could only stare at the other people in the room with him.

Here, after centuries of searching and wondering, laid the skeleton of the lost princess of their kingdom.