From The Metropolitan Opera website:
One of the most important—not to mention notorious—stage works of the 20th century, Lulu is the drama of a young woman who sexually and emotionally dominates a wide range of willing victims, both male and female. Herself a victim of society, she seems to embody all the frightening aspects of the human condition, a combination of primal instinct and distinctly modern amorality.
Berg’s score employs the twelve-tone technique pioneered by his teacher Arnold Schoenberg but in a keenly dramatic way that makes it accessible to all kinds of audiences. Berg died before completing Act III of the opera, and Lulu was first performed as a fragment. Efforts to finish the score based on Berg’s notes were hindered by his widow and only realized, after her death, by the Austrian composer Friedrich Cerha, in 1977.