Before there was Civil War, there was Madbomb. The two comic book stories are staples for Captain America fans, and many of them wondered whether the stories would be brought to the big screen. Of course, fans know Civil War recently entered the MCU’s canon \ this year - but did you know the block-buster almost didn't happen? According to the film’s directors, Civil War was very nearly turned by Madbomb’s zombie-like hoards.

Speaking with Entertainment Weekly, the Russo Brothers talked about the struggles they faced in securing Civil War as a storyline. “It was not a given that we were even going to do Civil War when we were talking about the next movie after Winter Soldier. So there was a period of time when we explored possibilities for Cap stories that did not include it,” Joe Russo explained.

Of course, the pair had been eyeing Civil War for Captain America’s third film for awhile. However, one problem stood between the directors and the storyline: Robert Downey Jr. The actor’s contract with Marvel Studios was completed ahead of the film, and negotiations to extend Robert’s deal was in a state of constant tug-of-war. As such, the Russo Brothers made sure they created a failsafe plan should Civil War go bust, and their search eventually lead the duo to look at Jack Kirby’s Madbomb comic.

Anthony Russo revealed that, “there was a period where we did discuss a third act that revolved around the Madbomb from Cap mythology. It didn’t have anything to do with Civil War, and if we couldn’t get Downey – in the very, very early conversations before we nailed him – somebody pitched the idea of a third-act that revolved around the Madbomb, which makes people crazy. It almost like zombifies them – but not literally.”

For those who’re unfamiliar with the comic, Madbomb stands as one of Captain America’s most notable storylines. The comic follows the hero after a bomb is set off in New York that turns civilians into mindless, violent machines of rage. Using sonic waves, the Madbomb wreaks havoc upon the minds of its unsuspecting civilians, and Kirby’s art depicts those infected as if they were a crowd of zombies. The event forces Captain America to dismantle the bomb and reverse its effects, leaving him to face off against tons of undead wannabes.

As for why the Russo Brothers were interested in Madbomb, they said the story pitted Captain America against a totally unexpected opponent. Joe said, “The notion of the Madbomb would have been Cap having to fight civilians and how he would he handle that. We were always trying to put him into these interesting moral conundrums because of his nature. That would have made a compelling third act because if civilians are the antagonists, how could he stop them without killing them?”

And, what’s more, the two said the hero would have to face-off against some old friends. While it’s unlikely Vision would fall prey to the Madbomb, some of the Avengers members would have fallen victim to the weapon’s crazy side-effects.

In the end, though, Robert Downey Jr. sorted out his contract with Marvel Studios and let the Russo Brothers scrap their Madbomb idea. However, fans of Agent Carter might recall that one of Howard Stark’s stolen weapons closely resembled Madbomb. Labeled ‘Midnight Oil,’ the weapon used chemicals rather than sonic waves to make anyone who inhaled its aerosol insanely violent. So, who knows? Perhaps Madbomb - or Midnight Oil, rather - could still show up in the MCU in the future.