When Armie Hammer was at risk of drowning while filming a key stunt for “The Man from U.N.C.L.E.,” not even Superman could save him.
In the movie opening Aug. 7, Henry Cavill — putting aside his Superman cape to play a suave CIA spy — rescues Hammer’s Russian KGB agent character from a watery death after he’s flung from a speedboat during a chase.
But that rescue effort went seriously wrong the first time.
To film the scene, director Guy Ritchie’s crew tied a cinder block to Hammer’s foot and sank him in a massive pool. There he waited, floating motionless and holding his breath, while Cavill swam to him from 25 feet above.
On the first take, Hammer failed to slip out of his tether as Cavill arrived to pull him up.
“It was like a Mafia execution gone wrong,” Hammer, 28, laughs. “Henry started swimming with me, but he was basically pulling me and this giant cinder block up ... so he did what you would naturally do and let go, and I sank all the way back to the bottom.”
Fortunately, a rescue diver at the ready swam over and stuck a breathing regulator into Hammer’s mouth.
Cavill, 32, tells the Daily News his co-star was cordial about the whole thing afterward.
“He was like, ‘Hey man, you let me go. But I’m really sorry because I still had a cinder block attached to my foot!’” says the British actor.
Hammer’s politeness and forgiving attitude clashes with his character’s brusqueness in “U.N.C.L.E.,” based on the popular TV spy series that ran on NBC from 1964 to 1968.
The pair play Napoleon Solo (Cavill) and Illya Kuryakin (Hammer), Cold War adversaries forced by their respective spy agencies to partner to fight a shadowy criminal organization. Hugh Grant and Alicia Vikander (“Ex Machina”) also round out the team, dubbed the United Network Command for Law and Enforcement.
With a dynamic score and Ritchie’s signature cinematic zip, the film is a throwback to the James Bond films of the Sean Connery era, full of exquisitely tailored heroes, gorgeous women who like to play rough and fleets of sexy sports cars, motorcycles and other vintage toys.
Early buzz around the film has focused on the characters’ chic costumes, particularly Cavill’s Solo, who has a taste for fine Savile Row-style suits.
But Cavill — who endured punishing workouts to appear buffed-up for shirtless moments in “Immortals” (2011) and “Man of Steel” (2013) — was happy just to be able to keep his shirt on.
“Taking your shirt off for a movie involves starving yourself, and that’s no fun when you are working 15-hour days,” Cavill says. “You look great, you have a six pack or an eight pack or whatever, but [it was a relief] just to focus on the acting.”
Hammer, meanwhile, had to get his vocal cords in fighting shape in order to pull off a convincing Russian accent.
The smallest misstep — says the Los Angeles native best known for roles in “The Social Network” and “The Lone Ranger” — would have him sounding like Boris Badenov from “Rocky and Bullwinkle.”
To nail the rhythms, Hammer spent hours watching tapes of native Russians speaking English and had a dialect coach on set monitoring his delivery.
“In the ’70s and ’80s, anytime a Russian was depicted in American cinema they were sort of these arch-villains. They were basically like, ‘Na-TASH-A!’” he says, mimicking the cartoon character, Boris.
“It can be really arch and really slapsticky, so you’ve got to stay on top of it.”