Straight-shooting, hard-hitting and fuming with contempt for the tobacco industry, “Addiction Incorporated” would be almost too exhausting to watch were it not for the folksy charm of its star witness. Nestled at the center of this relentless documentary, guiding us through a deluge of scientific evidence and corporate bobbing and weaving, is the scientist and whistle-blower Victor J. DeNoble, who reveals himself to be a born raconteur. His easygoing, self-deprecating narration is the film’s most valuable asset and the viewer’s best friend.

Hired by Philip Morris in 1980 to test nicotine alternatives for a more heart-healthy cigarette, Dr. DeNoble, armed with his Ph.D. in experimental psychology, quickly discovered just how addictive the chemical could be. When his test rats couldn’t get through their day without an ever-increasing number of nicotine hits — topping out at an astonishing 90 puff equivalents a day — Dr. DeNoble and his employers were equally shocked, though their reactions to the findings were very different.