MINISERIES PREMIERE: A Path Appears is a three-part documentary series which looks at tough problems, but also profiles and offers potential solutions, using empathic celebrities, and New York Times columnist Nicholas Kristof, as attention-getting guides. Tonight’s Part 1 looks at sex trafficking – but, quite pointedly, focuses on the United States, looking at the problem, and how to combat it, in Boston, Nashville, and Chicago. It’s very heartening – and, quite often, remarkably honest. Check local listings.