Two thrillers will collide this weekend at the multiplex as Leonardo DiCaprio's current box-office champ "Inception" zooms into battle against Angelina Jolie's "Salt." Both flicks feature serious firearms, brutal hand-to-hand combat and enough high-tension stunts to have even an audience-goer reaching for some Tylenol after the credits roll.

That's probably where the similarities end. Whereas "Inception" is the cinematic equivalent of a nesting doll, each layer opening to reveal another hidden dream world, "Salt" is a straightforward thrill ride -- eschewing a densely layered plot and CGI wizardry for 90 minutes of chases, gunfire and catch-me-if-you-can theatrics.

MTV News has given chase since the beginning, following the rather odd journey of "Salt" from its inception to its arrival on the big screen. Before hitting the theater this weekend, check out our cheat sheet for everything you need to know about "Salt."

How Edwin Became Evelyn

"Salt" stars Jolie as Evelyn Salt, a CIA agent specializing in Russian cat-and-mouse espionage. When a purported Russki defector shows up at headquarters and suggests Jolie is in fact a sleeper agent with plans to assassinate a world leader, she's forced to go on the run to clear her name. Unless, of course, she really is a double-agent ... duh duh duuuuh!

"Salt" keeps you guessing about Jolie's true identity, and the filmmakers themselves juggled various identities for her character as they struggled to get a green light for the picture. Evelyn Salt was originally Edwin Salt, back in 2007 when producer Lorenzo di Bonaventura was trying to get Tom Cruise to play the part. But di Bonaventura couldn't get a studio to bite -- until the filmmakers decided to switch the spy's gender and recruited Jolie to take on the role.

"You certainly have to do work on her character [in the script]," [article id="1638075"]di Bonaventura explained to MTV News[/article]. "Yes, that was hard work. But it was even harder with the characters around her. First, we did her character and said, 'That works, but everyone else seems kind of off.' So then we had to go back and do everybody else. It was a much larger undertaking than we previously expected."

My, How You've Changed

Filming kicked off early in 2009, and we got our first look at Jolie as Salt early in March.

It wasn't until the fall, though, that the first trailer for the film dropped. What we saw was an A-lister in full-on action-hero mode: rigging MacGyver-style weapons, blowing up tons of stuff and throwing herself off freeways onto speeding trucks.

It looked like dangerous stuff, and it was: Jolie ended up with a bloody cut on her face after a particularly perilous stunt that got her a trip to the emergency room. But it was worth it for the type of realistic action she and director Phillip Noyce were gunning to achieve. Just check out Jolie flying onto that oncoming 18-wheeler, using a rejiggered fire extinguisher to blow away the authorities and tasering a cop in an effort to get him to drive his car off an overpass while she's still in the backseat.

There's a Badass in All of Us

"Lara Croft: Tomb Raider," "Mr. & Mrs. Smith," "Wanted" -- Angelina Jolie has done the action-star thing before. But at this point in her life, with six kids at home, she took particular pleasure in her "Salt" stunt work.

"Maybe it's because I spend so much time at home with the kids that I really like to get out and jump on something and not be Mom for a bit," [article id="1643560"]Jolie told MTV News[/article]. "My kids are watching and rooting for me, so I want to impress them and be cool."

It wasn't just the stunts that attracted Jolie to the role, but the chance to play a character with [article id="1643472"]such complex allegiances[/article] -- one who keeps you asking, "Whose side is she on?"

"Maybe that's why I liked it so much, getting to play this character," she said. "I got to be all different people all the time. I think there is [a complex] element to all of us. That's why we like espionage."

Then Jolie added: "There's a badass in all of us. I've certainly got mine."

Check out everything we've got on "Salt."

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