This is the story of two Marys. Both are in their early 60s, heavyset, with curly reddish hair. But for years they have worked on opposite ends of the same issues. Mary McFate is an advocate of environmental causes and a prominent activist within the gun control movement. For more than a decade, she volunteered for various gun violence prevention organizations, serving on the boards of anti-gun outfits, helping state groups coordinate their activities, lobbying in Washington for gun control legislation, and regularly attending strategy and organizing meetings.

Mary Lou Sapone, by contrast, is a self-described "research consultant," who for decades has covertly infiltrated citizens groups for private security firms hired by corporations that are targeted by activist campaigns. For some time, Sapone also worked for the National Rifle Association.

But these two Marys share a lot in common—a Mother Jones investigation has found that McFate and Sapone are, in fact, the same person.

Scary.