This is more or less a full song, but it should loop fairly well, too.
This is one of my personal favorites of all the music I've done recently. It's interesting in that the musical patterns develop as the piece progresses; something like A A A A, A B A B, A B A C A B A C. Yeah, I know. That's not going to make sense to a lot of people. I often don't.
It's sort of quiet and mysterious, but it also invokes the sense of urgency you would expect from the title.