Directing his third feature, Ben Affleck has come up with a seamless blend of detailed international drama and breathtaking suspense, with just the right amount of dry humor to provide context and levity. He shows a deft handling of tone, especially in making difficult transitions between scenes in Tehran, Washington and Hollywood, but also gives one of his strongest performances yet in front of the camera as the film’s star.

It’s exciting to see the confidence with which Affleck expands his ambition and scope as a filmmaker. His first two movies, “Gone Baby Gone” (2007) and “The Town” (2010), were both smart and suspenseful, but both were intimate crime thrillers set within the familiarity of his hometown of Boston. “Argo” reveals his further mastery of pacing and storytelling, even as he juggles complicated set pieces, various locations and a cast featuring 120 speaking parts.

And the story he’s telling sounds impossible, but it’s absolutely true (with a few third-act tweaks to magnify the drama). Finally declassified in 1997, the daring rescue mission depicted here still didn’t make a huge splash even then. (Chris Terrio’s intelligent script is based on a selection from “The Master of Disguise” by Antonio J. Mendez and the Wired magazine article “The Great Escape” by Joshuah Bearman.) It’s a fascinating tale of bravery, international friendship and plain old moxie, one that’s serious-minded but crowd-pleasing.

Affleck cleverly foreshadows the Hollywood angle with a prelude told in storyboard form, efficiently providing background on the mounting dissent in Iran over the United States’ sympathetic stance toward the Shah. When protestors stormed the U.S. embassy in Tehran — recreated here frighteningly, viscerally — 52 people became hostages for the first of 444 days. But six employees sneaked out a back door and sought refuge at the home of Canadian Ambassador Ken Taylor (Victor Garber).

They became known as “the houseguests,” and with each passing week they spent there, their safety was in increasing danger. Surely their absence would be discovered, with deadly consequences not just for them but for their Canadian allies. Someone had to get them out … but how?

Enter Tony Mendez, a longtime CIA operative who specialized in such rescues — only he’d never had an assignment this perilous before. With the long, shaggy hair and full beard of the era (which makes him a dead ringer for Dave Grohl of the Foo Fighters), Affleck plays the part of the quiet, world-weary force who comes up with the craziest of schemes.

Mendez would fly to Tehran under a false name and pretend he’d come there with the six U.S. officials. They’d all pose as a film crew scouting locations for a sci-fi action flick called “Argo.” With fake passports in hand (provided by the cooperative Canadian government), they’d walk right out the front door, get on a plane to Switzerland and fly home to safety. As Mendez’s boss at the CIA (a commanding Bryan Cranston) puts it, “This is the best bad idea we have.”

It could all go wrong at any second, of course, with the capriciousness of those in power creating a dangerous variable. But the Americans had to know their parts inside and out, and the film at least had to look real enough to fool people — and for that, Mendez turns to an old friend, makeup artist John Chambers (John Goodman, with a wonderful mix of warmth and sarcasm). Chambers in turn hooks him up with veteran Hollywood producer Lester Siegel (a hilariously no-nonsense Alan Arkin), who puts the wheels in motion to give “Argo” the necessary authenticity: big ads in the trades, a production office on the Warner Bros. lot, even the media circus of a script read-through.

A cheesy “Star Wars” rip-off, “Argo” would have been total schlock if it had actually seen the light of day, and that’s a major source of humor that’s inside-Hollywood without being alienating. As Siegel says, if he’s going to make a fake movie, “it’s going to be a fake hit.”

Working with a top-notch production team, including cinematographer Rodrigo Prieto and composer Alexandre Desplat, Affleck creates a vivid ’70s vibe while moving fluidly between these intersecting storylines. While steeped in the trends and filmmaking style of the decade, “Argo” still feels immediate and relevant. Affleck’s best film yet is also one of the best films of the year.

“Argo,” a Warner Bros. Pictures release, is rated R for language and some violent images. Running time: 120 minutes. Four stars out of four.