An Al-Jazeera America investigation airing Saturday night spotlights heroin use and prescription drug addiction in Portland and Bangor. The episode of the television network’s series “Fault Lines” looks at the use of opioid painkillers and links to heroin use. Maine has one of the highest rates of prescription painkiller addiction in the country. The producer of the piece, Sam Black, is from Portland. The half-hour episode, “Opioid Wars,” will air at 7 p.m.