Wow. Here's a weird story and some awesome reporting from Mother Jones. The article's subhead sums things up about as well as anything else: "Mary McFate was a prominent gun control activist. Mary Lou Sapone was a freelance spy with an NRA connection. They are the same person." Now, naturally, gun control activists write large are worried that this isn't the only example and that their movement may contain more moles planted by the gun lobby.
Matthew Yglesias is a former writer and editor at The Atlantic.