The two talk about working on the film based on the James Ellroy novel

It's one of the most horrific deaths in American and Hollywood history - the brutal murder of actress Elizabeth Short in 1947. The investigation is still up in the air to this day, and is the focus of the new film, The Black Dahlia; the movie is based on the book by James Ellroy.

Josh Hartnett and Aaron Eckhart are the lead police detectives on the case; unfortunately, their two very different views on the case get in the way of their investigation. Josh is the young, go-getter, while Aaron is the veteran cop, who also has some side mob deals.

Another factor that comes in the way of their mission is Aaron's house-guest, Scarlett Johannson; Aaron had taken in Scarlett to protect her from a mob boss. Josh and Scarlett had an immediate attraction to one another, on screen and off screen.

We had the chance to speak to Scarlett and Josh; getting into the mood of the 1940's was pretty easy for both of them, considering they had two reliable sources - author, James Ellroy and director Brian DePalma on set. Scarlett said, "Luckily, I had what a lot of actors don't have which is the source, having the book. I mean, you read a script and you interpret the character's emotions through their actions and their words, but I had the perspective of Bucky's (Josh) character looking in on Kay. So I really used that as the beginning source to find the character. We talked about the character in regards to different scenes and that kind of thing, but Brian has a real respect for the time and space that an actor needs to prepare for something."

And getting inspiration came from within; "He was never overly personal about where I was getting my inspiration from or anything like that and always very supportive if I felt that I needed something more. We could be wrapping up the whole set, and I would say, 'Brian, I think that I need to do that take again.' He'd be like, 'All right, boys, bring everything back in.' He was really good about that, but we never went too much into depth about the character, no."

For Josh, he was involved with The Black Dahlia since the beginning of the idea to bring this true-life murder to life; the same time as writer Josh Friedman. In 1997, he was approached for the character, but because of delays and director changes, nothing happened. Then, Brian DePalma got attached and he got the ball rolling, keeping Josh in the movie. "Brian came onto the film about 2 1/2 or 3 years after I initially got involved; it was a different director at the time they hired me. But, I was hired to play Bucky when I was much too young to play Bucky; I was 23, but I recognized how great the material was and wanted to stick with it, so when the other director dropped out and Brian came on, there was a gap there of two years, where nothing was happening. When Brian came on, he hired me, just right off the bat. I went and talked to him and he didn't seem to have any interest in talking about the character or anything; we just sat down and had a cup of coffee and looked at each other and said, 'This is going to be fun.'"

The look of Scarlett's character was very important; she made sure it was perfect for who she was playing. "As far as the physical appearance of the character I really wanted her to look nothing like Hilary's (Swank) character or the Dahlia. So we thought that we would dress her in cream and beige and things that were soft because Hilary's character is so kind of hard and really a glam vixen."

Josh's look was pretty simple, except in the opening scenes where he's in the boxing ring against Aaron Eckhart. The two have a match to determine who is the 'best of the best;' the fight was deemed 'Mr. Fire (Eckhart) -vs- Mr. Ice (Hartnett).

Getting ready for that boxing match took an extreme amount of physical training from Josh. "I spent way too much time, really, boxing for this; I didn't need to, and I knew that I wasn't going to need to. I knew it was only going to be one scene in the film, but Ellroy makes a direct correlation between the way that Bucky acts as a fighter and the way that he acts in his life. He's Mr. Ice in both, and the way that he takes apart an opponent is very similar to the way he takes apart the case. So, for me, when I got into the ring, I felt I was starting to really understand the character, so I spent seven months boxing, five days a week, four hours a day, like they were training me to actually have a fight. And then, I would run for an hour, every day, it was intense; my trainers were really into it, they were killing me. The first day of training, or maybe the first few days, they put me in the ring to try and spar, to just show me that it wasn't going to be a cake walk. I think I made it less than a round before I was just passing out; you start to hyperventilate and you don't know how to keep your cool and you don't know how to start to pick apart your opponent, you don't know how to defend yourself. By the end of it, I was going seven rounds with 30-second intervals for time off, which is equivalent in a normal bout of going a full 10-round fight, so I was tip-top. It all helped me understand the character because it was all about being able to take my time and pick my opponent apart and act decisively at the right moments, but not until then. Bucky's a boxer, not a fighter, and that just gave me direct insight into the character."

However, even with the boxing training, he still wouldn't take on his co-star, Hilary Swank; she got into the boxing world, of course, for Million Dollar Baby. "Apparently, somebody said somewhere that she challenged me to a fight, but I wouldn't take her up on it."

The theory of Elizabeth Short's murder is still out there, and Scarlett wanted to leave it out there. That isn't something she wanted to even guess at. "I had read The Black Dahlia and that seemed like a palpable story. I don't know, though; I mean, that seemed to be - I felt that was interesting and was definitely a candidate for the truth, but who really knows."

As for Josh, he was just mystified by the fact that he was playing a pseudo version of James Ellroy. "He didn't tell me that until a week and a half ago. I guess that's a compliment, if he sees himself in what I did, but it was kind of obvious that he had written from a personal perspective because it's a first-person narrative and because he has said, many times, that this book was written in this way to exorcize the demons that were haunting him, due to his mother's death. The Dahlia and his mother's murder were inextricably linked for him, and so I assume that there was some sort of autobiographical tendency to the character. But, my job was just to take the work that was on the page cause if I tried to play James in this film, it would have been a wild film, man."

You can test out your theories when The Black Dahlia hits theaters September 15th; it's rated R.