Disclaimer: While this really doesn't fit with the BBC Merlin storyline, I'm still claiming that I don't own anything but my own made up plot.
The woman emerged from the Lake engulfed in a blinding white light. Her dark raven hair flowed to her waist in light waves and, if you looked closely, silver strands could be seen threaded through the locks. Draped in a deep blue that moved like the water in which she dwelled, the Lady drew closer to the shore.
When her eyes fixed upon his ,the breathe he'd been holding was suddenly forced from his body in a rush. When she spoke, it sounded as if an ethereal echo followed her every word.
"I know why you have come here, but I'm sorry. I no longer have what it is you seek."
"How can you know why I have come?" he asked. "How is it you know what I seek?"
She laughed a light, tinkling laugh at his words.
"Magic works in many ways, Merlin. Something you will learn one day."
Merlin gave the Lady a look of frustration, but proceeded to question her further. "Where is it, Lady?"
Her joyful expression turned to one of deep regret when she replied, "Not even the Lake is completely protected from evil magic, young one. She forced it from the depths many days ago."
"Morgan," Merlin hissed through gritted teeth. "Where is she? How can I get the sword back?"
"Morgan le Fey dwells in the Forest of Dread. How you choose to retrieve the blade I leave up to you." And with those words, the Lady returned to the depths of the Lake.
With a fierce look of determination upon his young features, Merlin set out to find the witch, Morgan le Fey, in the darkest reaches of the Forest of Dread. To retrieve that which was stolen would prove most dangerous, indeed. But to not would be fatal for Camelot. Arthur would need every advantage at his disposal in the many years to come. His knights, magic, and his Love will not be enough to keep him safe. No, he needed one final defense against what was coming. Arthur needed the one weapon that could defeat even the deadliest of creatures. The weapon forged in the ways of the Old Religion.
Excalibur.