Who isn't wondering what the next Metallica album will sound like?

Of course you are. And here's Kirk Hammett to explain to us:

"There is a really unusual theme that's working its way into the music," he replied. "I'm not really sure how to react to it. Maybe it's someone else trying to tell us that we should react to it, but a lot of the music has an eastern harmonic flair to it, a harmonic minor flair to it, and when I say harmonic minor, that could be construed as like eastern sounding or Middle Eastern sounding or maybe Arabic? I don't know if it's just the zeitgeist, a sign of the times, or maybe because like, you know, Middle Eastern culture is so prevalent, or maybe the negative things about Middle Eastern culture. Maybe artists are conscious, just want to shine light on the positive aspects of Middle Eastern culture, i.e. the music. But there's passages that sound, that use harmonic minor and dominant, and those sounds are distinctly Arabic sounding or Middle Eastern sounding, and you hear them in all the songs.

We can imagine a Metallica album making people think of the Middle East - a long, miserable, drawn-out series of unspeakable horrors that leaves everybody praying for a little bit of peace.