How and where does the battle between good and evil playout in this book.Most importantly who wins?

This really has much to do about the duality of human nature. Good and evil are major parts of this duality. One cannot exist without the other. In pursuing his scientific experiments and validating his work, Jekyll claims, "man is not truly one, but truly two." Thus, in Jekyll's view, every soul contains elements of both good and evil, but one is always dominant. In Jekyll's case, his good side is dominant, but he knows there is evil inside of him. However, as a respectable member of society and an honorable Victorian gentleman, Jekyll cannot fulfill his evil desires. Thus, he works to develop a way to separate the two parts of his soul and free his evil characteristics.Which one wins out? Neither wins if it means living without the other :there is nothing to temper each other. This eventually destroys  both Jekyll and Hyde.