It's official - Robert Downey Jr. is in final negotiations to don his Iron Man suit once again for the upcoming movie "Captain America 3." The film has yet to be given an official title, but is slated to begin production in the spring for a May 2016 release.  CNN reports that Downey's character Tony Stark will be pitted against Captain America in Marvel Comics' Civil War storyline.

The movie's plot focuses on the government passing a superhero registration act, which requires people with special powers to reveal themselves to the US government and help with law enforcement. According to Cinema Blend, Captain America and Stark will be on opposing sides of the act, with Stark being pro-registration and Captain America being anti-registration.

 Stark thinks that working against the law is pointless, and believes that super-powered people have been running around unregulated for far too long. On the other hand, Captain America argues that the bill infringes on civil liberties, considering that the law mandates superhumans to disclose their true identities to the government.

It is likely that Downey will be making a lot of dough from this movie deal - CNN reports that he's expected to earn about $40 million and a share of the box office for his screen time. He has already done well with his past three "Iron Man" movies, which have made $2.4 billion worldwide. Furthermore, his Iron Man character is expected to appear this summer in "Avengers: Age of Ultron" and "Avengers 3."

However, it is rumored that the deal for Downey to return as Iron Man in "Captain America 3" almost didn't happen. According to Variety, Marvel originally wanted to hire Downey for a small role, which he refused. Naturally, he wanted Stark to have a more substantial role in the film, more screen time, and a bigger payday. Thus, the new plot was born.

Overall, Downey has now been provided with a role that could well be played out into future Marvel films, including a fourth "Avengers." What's not to like about that?