My friends and I witnessed a psychological study yesterday afternoon [10/31/10] as well as a great musical.  I urge you to read the short statement of the original plot for this story, originally written as a serial at the turn of the century.
The Phantom of the Opera describes a young woman who is wounded by the loss of both her parents, and is haunted by a voice she hears from her childhood.  Her father told her she would be guided by the the “Angel of Music.”  That angel in the musical production becomes a dark figure, the “Music of the Night”  
The Phantom is the unloved, and undeveloped part of Christine, the part of her that yearns for integration and wholeness within her personality.  It drives her underground, at first kidnapping her, but in time attracting her with its power as well as its sorrows.  
Desperate for love and healing, this “phantom” part of her attempts to force acceptance and to assert its power to dominate her.  It seeks “marriage” by extortion and threat.  Receiving even a little love however, and feeling even a little acceptance, causes the Phantom to surrender.  The power of love within the Phantom is awakened, and he releases Christine.  All the persons she touches within her circle outside the underground are also released because Christine can connect with them in more healthy ways.  
This moment of liberation comes when Christine shifts from finding the Phantom abhorrent upon unmasking him.  She moves “out of denial.”  Gradually, she comes to accept the Phantom, and to feel compassion for him.   She voluntarily returns to him, and begins to approach him and even embrace him.  Eventually, she passionately kisses him, more so than required by the exigency of her situation as a “prisoner.”  
In the Pantages performance we saw on Halloween, the Phantom is not arrested or killed  He simply disappears.  Just as he emerged from Christine’s mind as she looked upon herself in the mirror at the beginning of the performance, he re-entered her psyche at the end.  His tyranny as an unhealed, fierce force of darkness has been dissipated by the light of love.