“The name of a man is a numbing blow from which he never recovers.” This quote from Marshall McLuhan opens the sharp and illuminating new documentary about former Congressman and failed New York City mayoral candidate Anthony Weiner, whose political career was derailed by a sexting scandal that unfortunately resonated all-too-perfectly with a last name that is a sometime-slang term for the part of the body he was sharing online. “I did the thing,” Weiner says in what we see is a characteristic mix of candor and denial. And the only thing harder to understand is how he thought he could do “the thing” without bringing down his political career is the willingness of his anguished wife, Hillary Clinton aide Huma Abedin, to literally stand behind him.

And then there is the question of why they would agree to this very film, recording agonizingly painful moments, both public and private. Weiner agreed to allow access to his former staffer, Josh Kriegman and his co-writer/director Elyse Steinberg for what he clearly hoped would be a film about his comeback and instead documented yet another downfall.

Cue the montage of late-night hosts making jokes about scandal #1, when Weiner accidentally sent out what he meant to be a private tweet photo of his bulging underpants to the whole world, followed by archival footage of him insisting he would not resign from Congress, followed by his resignation.

And then, what he saw as his comeback. “To clean up the mess I had made by running for mayor was the straightest line to do it.” He does not want to “live in this defensive crouch.” And yet, he acknowledges, “I lied to them, I have a funny name, and they don’t do nuance.”

While some people resist the prospect of “a punchline as a mayor,” he was ahead in the polls, with a group of bright, dedicated, young staffers. We see Weiner at his best, reaching out to voters and contributors, marching in a parade, passionate about the issues. And then comes scandal #2, the one where he texted nude photos to a young escort known as “Sidney Leathers,” using the name “Carlos Danger.” The second-saddest image in the film is the stricken face of Weiner’s campaign communications director as she must ask him whether he plans to deny the latest round of allegations, struggling with the deep ickiness of the situation on the personal and professional levels.

This movie does not attempt to explain why Weiner would undertake such behavior when he had to be aware of the professional and reputational risks, or why his wife, who clearly hates any kind of public exposure, stays with him, even though, as she says at one point, it is a nightmare. But the superbly edited film, with extraordinary intimate access based on deep trust, has a lot of insights about celebrity culture, media, and what we expect from politicians. Inevitably, the story of the frog and the scorpion comes up. Why do we make decisions we know will doom us? Is it our nature? And who is the frog and who is the scorpion in American politics, media, and culture? This movie suggests that the American electorate may be both.

Parents should know that this film includes strong language, material concerning sex scandals, some brief graphic images, and crude references.

Family discussion: Would you vote for Anthony Weiner? How much should a candidate’s private life matter in considering his or her suitability for office?

If you like this, try: the political documentaries “A Perfect Candidate” and “The War Room”