When working on the true-life ship hijack drama Captain Phillips, director Paul Greengrass went after as much authenticity as possible.
The very first time actor Tom Hanks in the titular role saw the Somali non-actors playing pirates was during the filming of the scene in which the pirates stormed the ship.
To increase the tension in that key scene, Greengrass kept the Somali cast separated from the rest of his ensemble, so that when they met for the first time on screen, the uncertainty of the situation would play out with genuine, visceral emotion.
"It was extraordinary, actually," Hanks says of the explosive scene in which the pirates confront the captain with their firearms. "I was on the deck with a couple of the actors who were in the film, and we went through as human beings what the characters went through.
"We had never seen these guys before, but suddenly we heard the pirates coming, getting closer and closer, their guns firing. And then, when they finally came in and burst - I mean, literally burst - onto the bridge, we saw these living, breathing guys for the first time."
It was a frightening moment, the actor says. "They're the thinnest human beings you've ever seen, and they're incredibly scary because their heads are huge, their teeth are really bad, and they were waving automatic weapons and pistols at our faces and screaming at us."
The hair on the back of his neck stood on end, he adds. "It was a very, very emotional and visceral moment. We were truly petrified.
"Now, that being said," Hanks continues with a chuckle, "that only happened for the first take. By the third take, the Somalis were all smiles, saying, 'Hey man, I just want to say, I can't believe I'm working with a guy who played Forrest Gump.'"