The Master and Margarita: Book Two

I found the first part of the second book absolutely tremendous with Margarita as a wild witch, Natasha as her furious second and that incredibly beautiful and twisted ball.
I was also gripped by Pilate and his intrigues (did more searching on Wikipedia to get it all straight!) - what a Machiavellian character!
The ending, I was less thrilled about however. There was both a desire to tie all the loose ends, but at the same time there are so many questions unanswered...

I understand there was the dichotomy between good and evil and I loved Woland's commentary about evil casting necessary shadows to protect life from too much light, but the meeting of the two stories I found unclear - how did one influence the other? Perhaps someone can answer that one for me!