Summary: I don't know how to write a summary without spoiler, so there is basic information and the rest I will tell you in the end of the story. Leroux-based.
There is sunny Sunday afternoon in the park and Erik with his wife enjoying each other in peaceful relaxation. It's everything what he ever imagine he could have.

He woke up because of a sun ray that was hitting his mask.
He opened his eyes unwillingly and he looked into the blue eyes of his beautiful wife. The blond hair that delineated her face looked like a halo.
How much he loved her!
She laughed with a beautiful laugh, which he loved so much, and she raised.
He loved their Sunday afternoons in the park.
He sat up and watched how his wife decorates her hair with the flowers that she had plucked around.
He felt calm in the soul, as he never felt before.
He felt no self-loathing, no inner pain, not even the fear that stood behind his hatred of humanity.
He could feel nothing but peace.
She looked at him with her big eyes and smiled again. She sat down opposite him and reached for the mask.
He didn't protest.
She was the only person that could takes off his mask, and he did not feel the internal pain it usually brought to him. There was no shouting of his subconsciousness and instincts that commanded him to defend when somebody touch his mask. When she removed his mask, he felt only peace and tenderness.
She put the mask behind her and smiled.
She was the first person what smiled at him so beautifully.
She picked up one of the flowers what decorated her long hair and gave it behind his ear. Then she smiled again.
How much he loved the little details of her face. He loved how her eyes spark when she laughed and how she could bring the tenderness even in the smallest moves.
He loved her laughing.
She closed her eyes and kissed him.
He closed his eyes in pleasure as he felt her lips on his. He raised his hands to touch her, but she pulled away. She smiled again and gently pronounced his name.
"Erik…"
It was the sound of her voice that forced him to open his eyes.
There was darkness, no light, no laughing. There wasn't any sign of presence of his wife.
It was just a dream.
He was back in his coffin, like a living corpse buried deep under the Opera house.
There was no one who could love him.
The voice that he had heard in his dream was still tingling in his ears, like the sound of a siren. And he couldn't do anything else but rose from his grave and rose to the surface to look at the sleeping girl who was the source of his torture.
When he was walking through the dark corridors he felt like Odysseus, hearing the beautiful voice of the sirens and he wanted to follow their voices. There was nothing more important in the world than going for a girl so often appearing in his dreams.
He came to the mirror that led away from his world. He was looking at the girl sleeping peacefully in the room behind the mirror, no idea about one night creature was watching her.
She was not afraid of him. Maybe she could love him.
She knew him as the Angel of Music.
She didn't know his name, his mask, his face.
She couldn't love him.
She knew only his voice.
A voice so different from anything other in the world.
The only thing that could be called as "beautiful" on him.
And yet, as he had a voice that could control the human mind, it was not him who was in the position of a siren.
It was she who attracted him in each of their singing lessons, as the siren did to the poor Odysseus, and he, like the sailor bound to the mast so that he could not move, was also bound to the underground world by the mirror separating their worlds.
He was bound to darkness by his face.
He wanted so much the girl to love him.
He hoped so much that he could become her loving husband.
He did not want to be an angel, he did not want to be a ghost.
For a moment and only for her, he wanted to be Erik.
Just Erik…

Author conclusion: I wanted to base this story before the book originally started. Christine knows Erik only like Angel of music and Erik is more and more attracted by her voice and wishes nothing more than love of Christine. This wishes appearing in his dreams and he more and more wanted to live those dreams in his real life. Yet he realise that his desire to be loved as he is, is almost inappropriate. And that's why he wants to spend all his time with the girl of his heart, even it means he will suffer by unfulfilled love. And then one day he will not be able to endure it anymore and there comes the beginning of original story by Gaston Leroux.