Back in October 2014, Marvel Studios president Kevin Feige held a special press event, where he laid out their entire Marvel Phase Three slate, which kicked off with the third Captain America movie, Captain America: Civil War. The producer and executive even brought out Robert Downey Jr. and Chris Evans, while introducing Chadwick Boseman as the new Black Panther. As it turns out, though, this whole scenario almost didn't happen, since Robert Downey Jr. wasn't contractually obligated to star in Civil War. While promoting the home video release, the Russo brothers teased one of the alternate comic book stories they were considering, which involves "zombies," so to speak.

Entertainment Weekly caught up with the Russo Brothers, who offered new details on what the third Captain America movie may have been, if Robert Downey Jr. had not agreed to come back. The actor had fulfilled his Marvel contract after Avengers: Age of Ultron, and had to re-negotiate a new deal, although this report claims that both the studio and the actor were "playing hardball." The directors revealed that it was "never a given" that Civil War be the third movie, and one of the alternate takes they were looking at centered on the Madbomb, that would have pitted Cap against a horde of zombie-like humans. Here's what Anthony Russo had to say about the Madbomb story.

"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. The charm of the Madbomb is that you turn hordes of people into berserkers. That was the physical challenge that Cap and company would have had to face."

Comic book legend Jack Kirby wrote and illustrated the Madbomb comic book story in 1976, which was a device similar to an atomic bomb. Instead of nuclear destruction, the Madbomb emitted sonic waves and radiation to destroy the minds of everyone within the blast radius. The device was created by a group of wealthy citizens known as the Elite, with plans to detonate it during America's bicentennial to create anarchy, so the rich could rebuild from the country's ashes. The victims were still alive, but had extremely violent tendencies that could not be controlled. If they would have went with this story for the movie, Daniel Bruhl's Baron Zemo would have been the one to set off the Madbomb. Here's what Joe Russo had to say about why they were considering this story.

"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?"

As you know, Robert Downey Jr. did end up signing a new deal, not only returning for Captain America: Civil War, but also coming aboard for Spider-Man: Homecoming and, presumably, Avengers: Infinity War. Once the actor returned, the directors scrapped the Madbomb concept, which was later used in the Season 1 finale of ABC's Agent Carter. Robert Downey Jr. is expected to return in Avengers: Infinity War which starts shooting this fall, so stay tuned for more updates on that project, and the rest of the MCU.