Spoiler alert: This story discusses the ending of "Expendables 4" (in theaters now). Stop reading if you don't want to know.

It's an alarming conspiracy theory: Is someone killing off the iconic old guys in "Expendables 4"?

First whopper of a clue: Ringleader Barney Ross (77-year-old Sylvester Stallone) dies early in the R-rated action film. It makes sense. It's been a long franchise run for Stallone, who was a comparatively spry 64 when he gathered fellow aging action stars for 2010's "The Expendables."

Yet going out early in a plane crash without unleashing dying fury seemed fishy, even if the franchise's remaining OG crew Lee Christmas (Jason Statham, 56), reading glasses-wearing sniper Gunner Jensen (Dolph Lundgren, 65) and Toll Road (Randy Couture, 60) rally around Ross' death and their comrade's fried arm. The charred limb, with Ross' telltale skull ring, is the only thing left.

Then, brace yourself, Toll Road gets stabbed in the stomach and Christmas faces such doom he speaks to his deceased friend: "Looks like I'll be seeing you soon, Barney."

"When you're an Expendable, you're allowed to die," says director Scott Waugh. "That's your job."

Does Sylvester Stallone's Barney Ross die in 'Expendables 4'?

Barney sure seems dead. He's the only one on the transport plane that explodes into flames. But Expendables don't do DNA tests to make sure it's actually Barney in the rubble (sorry). They just run and gun for revenge against villain Rahmat (Iko Uwais) with newcomers Gina (Megan Fox), Easy Day (50 Cent) and CIA operative Lash (Levy Tran).

But as they try to stop a world-altering nuclear explosion plot masterminded by the mysterious terrorist known as Ocelot, Toll Road is stabbed and Christmas is down to final bullets in a gun battle.

"We liked the idea that after Barney dies, we're just going to pick all the old guys off one by one," says Waugh. "Even Statham is going out gloriously with that cry, 'Make my sacrifice count!' That's the tongue-in-cheek aspect of the franchise."

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In reality, everyone survives. Barney rises (literally) in an ascending helicopter, just in time to shoot up the double-crossing Expendable newbie, CIA agent Marsh (Andy Garcia), who is the secret terrorist Ocelet. (Expendables don't do background checks.)

Marsh is so destroyed that his smoldering remains help "Expendables 4" earn its R rating.

Christmas speaks for America when he joins Barney in the helicopter and wonders aloud, "Hey, you're dead? What the hell is going on?"

Who really died in the 'Expendables 4' plane crash?

After saving the world, again, Barney has time to explain what happened with the fake death stuff. It all has to do with Barney's ring. The prized ornament was stolen by rough bikers earlier in the movie, leading to a bar fight between Christmas and the diminutive biker dubbed "Jumbo Shrimp" (Mike Möller). Lee walloped him as Barney watched (bad back), but that was not the end of Jumbo Shrimp.

Turns out, Barney secretly stowed the gagged Jumbo Shrimp on his plane for the mission. As the plane went down, Barney pulled Jumbo out of hiding, placed the ring on Jumbo's hand, and put the wide-eyed foe in the fiery pilot's seat. Then Barney bailed secretly and safely by parachute, keeping his death secret.

Barney explains he had to fake his own death in order to draw out the Marsh treachery he saw coming from past missions, a covert move only taught in action star spy school.

Toll Road survives, Lee escapes. Stallone and Statham, the still-breathing core Expendables, are set up for any potential fifth movie. That will require the franchise wheels to hold together at the box office with a 16% favorable rating on the review site RottenTomatoes. (Expendables don't read reviews.)

Why is 'Expendables 4' rated R?

There are many reasons why 2014's "Expendables 3" flopped at the box office with $39 million compared to 2012's "Expendables 2," which tallied $85 million. Waugh believes the "Expendables 3" PG-13 rating compared to the previous films' R ratings played a big part.

"They really tried to soften the brand to go PG-13 and not have all the blood. And the audience got resentful," says Waugh. "They love the authentic, graphic violence."

"Expendables 4" wears its R like a red badge of dumb courage, even promoting the restricted rating in the trailers. The payoff comes in moments like the chase scene where Christmas explodes the top half of a foe's body with a massive gun.

"We can do that, we're 'The Expendables,' " says Waugh. "It's really a testament to the first two movies."

What happened to the nuclear bomb in 'Expendables 4'?

Just when it seemed Marsh would succeed in delivering a world-changing nuclear bomb, with the Expendables taking the blame, Barney and Christmas rally to save the day. Not only does Barney obliterate Marsh, but he sinks the ship carrying the nuclear bomb, which explodes underwater.

The nuclear explosion is a big leap from "Oppenheimer" reality. But Waugh insists the explosion is based on U.S. Navy underwater atomic tests.

"So all I can say is the Navy did it," says Waugh. "So why not re-create that onscreen?"

Speaking of bombs, the final scene features all the celebrating Expendables gathered in a bar, where they collectively raz Christmas for yelling, "Make my sacrifice count." There is a dramatic line even Expendables don't cross.