NBC News’s Lester Holt on Wednesday night anchored “NBC Nightly News,” substituting for Brian Williams, who was said to be “on assignment.

Accurate: Williams went to Russia for an exclusive interview with famous National Security Agency whistleblower Edward Snowden, an NBC News source confirms.

That’s not all. Glenn Greenwald, who helped boost the Guardian to a public-service Pulitzer Prize, showed up as well. The result of all this on-the-sly travel will be a tripartite NBC News interview extravaganza: one session of several hours with Williams and Snowden, which will constitute the majority of the on-air presentation; one with Williams and Greenwald; and a third with Williams and both Snowden and Greenwald. As opposed to conducting the interview, which he did previously with Snowden, Greenwald will be an interviewee in this go-round. The NBC News primetime special from the interview will air on May 28 at 10 p.m. EST.

The timing works for Greenwald, who recently embarked on a book tour for “No Place to Hide: Edward Snowden, the NSA, and the U.S. Surveillance State.”

The interview is sure to produce some memorable exchanges, but the way that NBC News pulled off the coup is noteworthy as well. NBC News has a “collaboration agreement” with the outfit that these days publishes Greenwald’s work — First Look Media, the venture funded by billionaire and eBay founder Pierre Omidyar. Greenwald is a staffer at the Intercept, First Look’s digital magazine on national security matters.

So did the Greenwald “collaboration agreement” snare the Snowden interview for NBC News? For starters, Snowden is a strong-willed sort unlikely to take interview orders from anyone, though his relationship with Greenwald is airtight (he’s in a just-published selfie with Greenwald & Co. in Russia). According to the network source, NBC News approached Snowden via several avenues, one of them being through Greenwald. Though Greenwald didn’t negotiate the terms of the agreement, the NBC News source concedes that Greenwald is among a small number of people who can assist in making contact with Snowden, who is living in Moscow.

The agreement between NBC News and First Look Media contains no financial terms, says the NBC source. It’s merely what the network calls a co-reporting arrangement, in which the two participating outlets share resources in working on the almost always complicated surveillance stories that spring from the Snowden document dump. Responding to an e-mail inquiry, Greenwald himself says that the agreement “simply provides that we will work together on selected NSA stories, on a story-by-story basis, when it will help the reporting to do so.”

To complicate matters a bit, Greenwald worked as a freelancer for NBC News in between his departure from the Guardian and the launch of the Intercept. Together they produced four stories, with Greenwald receiving $750 a pop. In this February investigation, for instance, NBC News used Snowden documents to expose how British intelligence waged war on hackers. Greenwald is credited as a “special contributor” for the piece. In January, NBC News published a story stemming from Snowden documents on how British intelligence spied on Facebook and YouTube. That one, too, listed Greenwald as a special contributor.

The special contribution of Greenwald to these projects is indeed quite special. He holds the documents that he secured through his early, fascinating journalist-source relationship with Snowden, a topic of “No Place to Hide.” That said, Greenwald didn’t merely execute a document hand-off operation with NBC News: “I went back and forth multiple times with the editing of the articles,” says Greenwald in an e-mail. “I participated in numerous calls and meetings about how we were going to present the material to the public. I was every bit as involved in the NBC articles as I was in the reporting I did for the Guardian and every other media outlet.”

Partnership yields positives for both sides: First Look and Greenwald harvest the heavy investment of a mainstream news outlet in the whole Snowden-based oeuvre, a not-insignificant consideration in an environment where some yahoos are still questioning the merit of these stories. And they get exposure to a television audience that’s perhaps not following the plume of First Look-obsessed Twitter account holders. Plus, the Intercept’s staff can juggle only so many of these Snowden-based stories at a time. Greenwald and colleague Laura Poitras & Co. have collaborated with a number of news organizations over the past year in an attempt to publish as much material as possible.

NBC News, for its part, gets documents and a legitimate reason to use the most illegitimate word in television: “Exclusive.”

Whatever the formal arrangements between NBC News and First Look, they apparently place no cap on the number of segments that NBC News can do to promote Greenwald’s “No Place to Hide.” On May 12, for instance, NBC News national correspondent Kate Snow did a sit-down on “NBC Nightly News” with Greenwald that plugged the book right at the top of the segment: “Edward Snowden may go down as the most famous whistleblower of our time. And now the man who he leaked secrets to, Glenn Greenwald, has a new book revealing more allegations of widespread surveillance by NSA employees,” said Snow.

Just this past Sunday, NBC News’s Pete Williams, in a segment on “Meet the Press,” took questions from social media for Greenwald and introduced the guest this way: “He’s the man who first revealed Edward Snowden’s leaks about U.S. surveillance to the world. Glenn Greenwald tells the story of how it happened in a new book, ‘No Place to Hide,’ and has been talking about it all week.”

More! On the May 17 “Today” show, Holt introduced Greenwald and his book: “It was nearly a year ago when Edward Snowden ignited a worldwide firestorm by leaking classified NSA documents to the press. And now one of the reporters who broke that story, Glenn Greenwald, has a new disclosure. He’s revealing the story of how those intelligence files ended up in his hands in a new book called ‘No Place to Hide.’ ” Holt called it a “fascinating read.”

Other big-time outlets, too, have given prominent placement to book-related interviews with Greenwald, including CNN (chat with Anderson Cooper) and the Colbert Report.

Over the past year, Greenwald has occupied a double role in this spellbinding story. For part of his day, he works as a dogged reporter, pushing the story of surveillance overreach to another precipice. For another part of his day, he works as a player in that very story, bashing the U.S. government and those he views as its courtiers for failing to stick up for the truth. The sit-down with Williams and Snowden marks the melding of these two roles, as Greenwald answers questions in an interview that he facilitated to some degree.

Last August, The Washington Post’s Paul Farhi reported that Greenwald had held “preliminary talks” with TV networks to produce a Greenwald-on-Snowden interview. The plan didn’t work out.