X orders Nikki to kill mary.  Nikki returns to the church, where he finds Mary waiting for him.  Two hours pass, and he goes to her, as she walks the halls, looking at paintings and singing.  He tells her the Syndicate wants her dead and that he is to kill her.  He also tells her he killed Father William.  Mary is overwhelmed.  She begs Nikki to make love to her, then kill her.  Nikki refuses to kill her, instead asking her help in stopping X and the Syndicate from doing any more damage.  He tells her he has seen the wrong in X's plans and wants to kill him.  They make love, on the alter, and Nikki leaves to confront X, thinking how alike he and Mary are in their lives.
    This songs serves to tell an important piece in the story, indeed the turning point.  It is not particularly deep, but two images resurface.  The idea of the candles comes back, still with one unlit.  With his new resolve, Nikki will only light the last candle when it signifies X's death.  Mary, ever selling herself, allows Nikki to take her on the alter, just as Father William did.  This is important, because the alter is the center piece of christain religious practice; the table of God.  To have premarital sex on it, with one of the two being a nun, represents the ultimate defiance against religion.
    Two points about the music.  The lyrics are mostly a dialogue between Nikki and Mary.  During Nikki's parts, the music is fast and anxious, and Geoff Tate sings.  Nikki is tense and ready for action.  During Mary's parts, the music is slow and peaceful, with a hint of sadness.  Mary is sullen and subdued.  Pamela Moore, the voice actress playing Mary, probably sings.    If not, then it is Geoff Tate doing his Geddy Lee impression.  The guitar solo is wild and frenzied, and we hear an orgasmic female voice.  Nikki and Mary are making love during its course.