Alex Gibney likes to take on challenges — lots and lots of challenges. The latest are the Stuxnet worm and cyberwarfare. They’re the subject of his new documentary, “Zero Days.” Showing something super-secret and effectively invisible: Now, that’s a challenge.

Since winning an Oscar for “Taxi to the Dark Side” (2007), about the United States’ use of torture in the war on terrorism, Gibney has averaged more than two documentaries a year.

Subjects have included political corruption (“Casino Jack and the United States of Money,” 2010), Julian Assange (“We Steal Secrets: The Story of WikiLeaks,” 2013), and two very different kinds of misplaced worship (“Going Clear: Scientology and the Prison of Belief” and “Steve Jobs: The Man in the Machine,” both 2015).


Gibney’s documentaries may vary wildly in subject matter — don’t forget the ones about Hunter S. Thompson, Ken Kesey, Lance Armstrong, James Brown, and Frank Sinatra, and the cooking show with Michael Pollan — but they have at least three things in common: seriousness, ambition, and a willingness to push back. That willingness can take two forms: pushing back against subjects who want to deny access and against subject matter that doesn’t necessarily lend itself to visual presentation. In that regard, “Zero Days” is a two-fer.

The Stuxnet computer worm was reportedly developed by US and Israeli intelligence services to disrupt Iran’s nuclear efforts. It was insidious and highly effective. To this day, neither the United States nor Israel has officially acknowledged any involvement with Stuxnet.

Until the Israelis overreached and altered the Stuxnet code — or so US intelligence-community sources allege in the film — it remained unknown. Gibney starts out by showing how various computer-security types came across Stuxnet and figured out what it was. Kaspersky Lab’s Eugene Kaspersky and Symantec’s Eric Chien and Liam O’Murchu make for excellent talking heads. They know their stuff, scarily so, and talk about it with missionary zeal.


This is a world very few of us have familiarity with, which makes it all the more fascinating to learn about. The first half of “Zero Days” (zero day refers to a type of computer vulnerability) is a high-tech espionage thriller, really, and all the more thrilling for the story it tells being real. Gibney handles things with sleek assurance. If some smart person ever gets around to producing a movie of the collected works of William Gibson, Gibney should be a lock for director.

Part of the fascination this material holds is that even if we’re not familiar with it specifically, we’ve been exposed to it generally, in the form of hacking. It’s the larger issues relating to cyberwarfare that dominate the second half of “Zero Days.” We hear from such talking heads as David Sanger of The New York Times, and Michael Hayden, former head of both the Central Intelligence and National Security agencies. Larger implications loom. Making the prospect of mutual assured cyber-destruction compelling on screen is a challenge Gibney doesn’t quite meet. That makes the issue no less important, obviously, but it does mean “Zero Days” loses a bit of steam.

What may the most ingenious thing about the documentary is Gibney’s treatment of anonymous sources. There’s one NSA staffer in particular — seen in shadow, her voice altered — who’s the real star of “Zero Days.” Her reveal is at once solid journalism and dramatic tour de force. It’s a challenge Gibney meets with ease.


★ ★ ★


Written and directed by Alex Gibney. At Kendall Square. 114 minutes. PG-13 (some strong language)